My character has ability to absorb and convert kinetic energy of punches ,or anything but only kinetic energy absorbing and convert that into chemical energy .Is this possible in this real world ? what structure would require to convert kinetic energy to chemical energy? and what materials is they made of need to absorb and store massive amount of kinetic energy ?
With minimal hand-waving you can do it.
I don't believe there are any natural examples of biological organisms converting (non thermal) kinetic energy into chemical energy. However, since we're talking about super powers, a certain amount of hand-waving may be allowed. If so all you really need to say is that your character's muscles are reversible. Normally a person's muscles convert chemical energy into kinetic energy, but for your character it can go either way. Special muscles is the only thing you need for this to work. The human body already has mechanisms for storing chemical energy. As for massive amounts, it depends on your definition of scale.
It sounds like a modified version of, or rather based on, a piezoelectric crystal: kinetic energy deforms the crystal, the deformation produces a difference of potential and the difference of potential is transferred to some chemicals which store this energy.
The main problem seems to be the transfer rate: a punch or a blow have a very short duration, and all the chain above should happen in that timescale. It can be difficult or impossible if the amount of energy involved is high enough. Something like trying to capture the discharge of a dam with a glass of beer.
It's fine as superpowers go, but decide what the limits are
As the other answers say, you can probably get away with hand-waving it. Maybe you want it to work for bullets - that's no harder to explain than actual flying. But decide what the limits are. Maybe it can stop a handgun, but not a sniper round. Maybe it can't stop an aeroplane, maybe it can. If you have the character proactively make a plan to circumvent whatever upper limit you choose, it will feel believable (and their opponents should be able to rely on that upper limit as well, and rely on the fact the absorber character will have to work around them).