when i drive my s2 on and off freeway ramp, i have to correct the steering wheel at least 2 times.
does this happen to you guys also?
however, when i drive my friend's BMW, i can just get over without adjust the steering wheel at all.
my car had one accident before.
so, can it be the frame damage that causes the problem?

 

What a BMW can or can't do under similar circumstances may have no bearing on what's going on in this scenario. A BMW may behave the way it does because of tire size, suspension settings, vehicle weight, wheelbase, degree of power steering assist, etc. What you need to do is to duplicate this manouver in an S2000 that has NOT been in an accident before and is otherwise similar to your car in terms of mods.
Did you have to do this same correction BEFORE your car was in an accident? Has that particular piece of road changed in any way since then? Has your car been properly repaired and re-aligned since the accident?

 

"Did you have to do this same correction BEFORE your car was in an accident? "
i don't remember that's why i want to check with you guys.

"Has your car been properly repaired and re-aligned since the accident?"
yes
"Has that particular piece of road changed in any way since then?"
happens on almost all large radius freeway ramps.

 

I think it's going to be really difficult for anyone over the internet to give you a definitive answer. The need to make steering corrections will depend upon the kind of tires you have, the pressures in those tires, the curvature of the road itself, the road surface condition, the speed at which you negotiate this curve and what you are really doing when you say "correct" the steering, none of which you have given any description of (not that it would be possible for any of us to duplicate them or have had experience in those exact parameters). And since you can't remember if it did it before the accident, my suggestions in my first reply still stands. Using another kind of car for reference may not be relevent.