Charli D’Amelio was in attack mode after her sister, Dixie, joked about killing her dog, Rebel … dramatically storming out of a family meeting about Rebel’s eating habits.

The sisters went at it on the latest episode of their Hulu series, “The D’Amelio Show” … 19-year-old Charli and 22-year-old Dixie were talking with their parents, Marc and Heidi, about moving houses when the focus shifted to Charli’s pup.

Dixie calls “Charli’s fat dog” a monster, with Heidi agreeing Rebel is pretty big, adding, “She’s gonna die” and they need a plan.

That’s when Dixie dropped the sarcastic bombshell, quietly saying, “Execute her?” — which didn’t sit well with Charli, at all.

She immediately blew up, telling Dixie, “What the f*** is wrong with you? That’s so mean, you can’t put that out in the world.” Mom agreed.

The younger sister left a lot of tension behind as she walked out of the convo … and Dixie rolled her eyes, calling her sister “a bitch.”

BTW, Marc obviously didn’t want to fuel the fire … telling producers the fam “can’t afford them not to be speaking.”