Is my dad the only one that when he gets mad he starts hitting and punching himself ?

Better himself than hitting you.

That sounds like some self sabotaging behavior that may become serious or dangerous left unchecked...

He hit the wall and slammed doors when he was really mad. No doubt he had anger issues and I hold him to that strongly. Went as far as to truly hate the man for it sometimes. But he's changing for the better, and I know that he'd never lay hands on family, with the exception of sibling fights I guess. I know he loves me.

He had always done that since I remember nothing had happened. He does it when doing something confusing example when putting together furniture lol or when someone goes against of what he says.

lmfao

Well I don't wanna psychoanalyze a stranger. I'll just say this. Healthy communication is key to understanding others. If you have no reason to fear him, then just have a talk with him about it AKA a heart to heart. You can tell him how you feel about it - if you feel anything about it, and maybe ask him what he thinks about when he does that to himself.