When the hitting force of hammer head on ore is just at the collision center of the hammer head(or hitting center),the collision counterforce of hammer pin hole and shaft can be completely eliminated,thus reducing hammer wearing and enhancing crusher efficiency.Through the calculation formula of collision counterforce on hammer pin hole,the article establishes the finite model of hammer,and obtains the stress on each point of the hammer surface through loading hitting force on different points of the hammer surface.The hammer structure size is optimized according to the result.