Strangle list (off-continuity episodes are listed like this)
How does Bart survive all the stranglings he recieves? Only he knows! But here's a long list of every time it's happened:

Simpsons roasting on an open fire: (by Homer heard only) at the end when Bart keeps interrupting the song.
Homer's Night Out: (attempted by Homer) when Bart shows Marge the photo. (Note that Marge also strangles Homer here, so it runs in the family!)
Simpson and Delilah: (by Homer) when Homer finds out Bart broke his Dimoxinil hair formula bottle. (Note: Bart gets Homer to stop by saying "I love you Dad!")
Treehouse of Horror: (by himself) Bart pretends to strangle himself to try and scare Lisa
Blood Feud: (by Homer) when Bart tells Homer he sent the insulting letter to Mr. Burns.
Like Father, Like Clown: When Bart makes fun of Homer at dinner. "Boy, you don't have to follow in my footsteps." "I won't even use the bathroom after you!" (Note: Krusty's father did the same thing to him in a flashback right before it happened)
Stark Raving Dad: (by Homer) when Homer finds out that it was Bart's lucky red hat turned his clothes pink.
Three Men and a Comic Book: (by Martin and Milhouse) when the boys fight over the first edition of Radioactive Man, they strangle each other.
So It's Come to this: A Simpsons Clip Show (by Homer) After Bart admits he shook up the can of beer, Homer slowly wakes up from his coma and strangles him.
The Front (by Homer)
Bart's Girlfriend: (by Homer) when Bart won't admit to stealing the church money, even though he really didn't.
'Round Springfield: (by Homer) When Bart wakes up after his operation. "It's wonderful, you're alive!" "No thanks to you, Homer." (Dr Hibbert is nearby and stops Homer)
Mother Simpson (by Homer) When Bart calculates all the presents that his grandma (Mona) ows him. ( Homer stops when Mona tells him off)
Homer's phobia (by Homer) when Bart tries to slap Homer, but ends up punching him.
Simpsoncalifragilisticexpialad'oh-cious: (by Homer) Right after Shary Bobbins leaves the Simpson house. (Bart was pushed through the glass window- ouch!)
All Singing, All Dancing (by Homer) Bart makes Homer angry during the song by singing "You're as lame as Lee Marvin..."
Miracle on Evergreen Terrace (by Lisa first, then Homer) When the family find out what really happened to the presents.
Dumbbell Indemnity (by Homer) through the bars in Homer's jail cell
Girly Edition (by Willie, using his arm, through the window) After Bart destroys Willie's shack with a lot of creamed corn. Later, by Lisa when she becomes jealous of Bart.
(Treehouse of Horror IX (by Homer): When Snake's hair jumps on Bart's face, Homer tries to stop it by punching it, inadvertedly punching Bart in the face. Bart yells "That's my face, you idiot!")
Marge Simpson In: Screaming Yellow Honkers (by Lisa, using her arm) After Bart upsets Lisa by donning a chicken nude and becoming "Baron von chicken pants".
Guess Who's Coming to Critisize Dinner?: When Bart makes a joke about Homer in a restaraunt.
Last Tap Dance in Springfield: (by Homer) in Homer's eye test, when Homer reads out what Bart wrote: "I 8 PP". (note: Homer keeps strangling here until he can see Bart properly through the lens)
A Tale of Two Springfields: (by Homer) After Bart plays a trick on Homer using the phone. Homer wraps the phone wire around Bartr's throat and strangles him with it, Bart hits Homer on the head using the phone, and the two collapse on the floor, tired out.
Lisa the treehugger (by Homer) Homer yells "You call that saying grace?!"
Children of a Lesser Clod (by Homer) when Bart and Lisa show the "truth" about Homer in front of a large audience
(Treehouse of Horror XII (By Homer) When Bart thinks the now bearded Marge should be in a freak show. Note: the strangle makes Bart's neck stretch a long way because of the gypsy's curse)
The Parent Rap: (by Homer) When Homer and Bart are slapping each other using the cord that joins him and Bart together, Homer wraps the cord around Bart's neck and pulls Bart towards him with it. (Bart retaliates by whipping Homer with the cord)
Brawl in the Family: (by Homer) Bart cheats as the family are playing monopoly, and an argument ensues that leads to Homer choking Bart. Marge and Lisa try to pry them apart without success. Maggie calls the police, and the police soon arrive with Homer still attacking Bart. The police eventually stop the fight with a robot that sprayed taffy at them
Blame it on Lisa: (by Homer) after Homer assumes Bart was lying over making expensive calls to Brazil.
Half-decent proposal: (by Homer) When Homer is trying to record a tape for Marge, and Bart interrupts. Homer lunges for Bart, bashing into the camera, swinging it around to view Homer throttling Bart and crying for Marge at the same time.
I am Furious Yellow: (by Homer) After Homer finds out Bart made him the laughing stock of the town in Bart's Internet cartoon, "Angry Dad" and shortly after when Bart suggests Homer should be played by John Goodman in the cartoon
Bart vs. Lisa vs. the 3rd Grade (by Lisa) Bart and Lisa strangle each other, and later Lisa strangles Bart using her necklace
Large Marge (by Stampy the elephant) as Stampy tries to eat Bart, Homer and Milhouse
Helter Shelter: (by Homer) When the execs are wondering if the Simpsons are good for reality TV
Barting Over: (by Homer) in Bart's new apartment, when Homer becomes jealous of Bart's expensive couch and TV. Earlier in the episode, Bart strangles Homer, first using his hands without success, but then using Homer's belt which proves pretty effective (!)
The Three Gays of the Condo (by Homer) "I love watching you guys fight - it's my earliest memory!"
C.E.D'oh (by Homer) Homer and Bart tussle on the baseball diamond. Homer eventually ends up strangling the boy, until Bart bites him.
Brake My Wife, Please: (by Homer) at the dinner party, when Homer says that Marge has done so much without getting anything in return and Bart says "Except a place to live and free food!"
My Mother the Carjacker: (by Homer on a picture): Homer is strangling Bart - but Homer is also being strangled by Mona
The Fat and the Furriest: (by Homer) after Bart says "We'd rather have a live sissy mincing around the house than some dead hero anyday" when Homer is attacked by a bear on TV
Today, I am a Clown: (by Homer) after Bart says to Homer that his show failed because he blew it and lost his strangle hold on the audience
Smart And Smarter (by Homer, twice) During Homer and Bart's fight in the bathroom
The Way We Weren't (by Homer) When Homer discoveres Bart's been using his beer to play spin the bottle
Catch 'em If You Can (by Homer through a wall) When Homer overhears Bart saying insults about him from the other room
Fraudcast News (by Homer) when Bart compares Homer to a monkey
Sleeping With The Enemy (by Homer) when Homer won't believe that Bart really didn't cheat on a test
She Used To Be My Girl (by Homer) For no reason, 3 times in this episode (...)
There's Something About Marrying (by Homer) Bart tells Homer he should go on a diet
Mobile Homer (by Homer) Bart makes demands for Homer and Marge to make up before he stops the RV, "Raise my allowance!" being the one that annoyed Homer. Homer strangles Bart with both the Simpsons' car and RV in motion
Home away from Homer (by Homer) After Homer notices Bart waching the girls on the webcam
The Girl Who Slept Too Little (by Homer) On a tape of Lisa as a baby, Homer's choking a young Bart to Marge's annoyance.
Milhouse of Sand and Fog (by Homer) Bart and Homer are trapped in the river, and Bart admits he was the one who caused Marge to become angry with Homer
The Italian Bob (by Homer) At the airport, Bart mentions Homer didn't take out any insurance on vacation. Homer chokes him, but Bart uses Airport equipment to repeatedly bash Homer until he releases him. Homer however falls on top of Bart.
(Homer strangles Bart on a fictional tale in The Wettest Stories ever told)
Regarding Margie (by Homer) As the family take Marge around the hospital, Bart compares the house to a pile of puke. Homer throttles the boy, but Marge, having suffered amnesia, can't believe what she's seeing. Homer stops and says Bart's cool with it, until Bart complains that it hurts to swallow, in which Homer resumes strangling.

Strangling seems to run in the Simpson family - and throughout Springfield too!