could be lots of things,
first what is bow poundage? are you reaching for the sky when drawing?
draw should be smooth,
shouldnt hold the draw too long,
forward hand should be comfortable, more like resting the bow on your hand instead of holding and grabbing,
it should be able to rest on your hand between your thumb and forefinger even with you hand open.
when releasing like other poster stated, even pressure till it releases, much like a gun trigger, dont pull the trigger quickly/suddenly
when released, bow should slowly drop away on your forward hand
if form is ok, might be the bow/arrow setup, are feathers getting worn at all? they may be making improper contact with the rest