The relationship between the rigidity of the isokinetic equipment and its isokinetic performance was studied. By establishing the Simulink simulation model of isokinetic equipment, the difference of isokinetic performance of the isokinetic equipment with different rigidity in different forms of force was compared, and the check test was carried out by using experimental platform. The research results show that the isokinetic performance of the system with the rigidity of 200 N·m/rad is the best. The acceleration and deceleration stage of the rigidity isokinetic equipment is stable, the output speed response is fast, the maximum overshoot is small, simultaneously, the stability of the output speed is good, the antiinterference ability is strong.