Abstract: In order to conclude a general expression of ultrasonic degradation kinetics for polymers, the general applicability of the common kinetics equations was discussed. The common ultrasonic kinetics equations of polymer were used to compare the fitting accuracy for original data collected from all available literatures. The fitting accuracy of the kinetic equation was evaluated by remainder standard deviation. The fitting results indicated that the first order equation and the second order equation were more accurate and could replace other kinetics equations. Thus, a general power law expression (GPLE) of ultrasonic degradation kinetics for polymers, -dMtdt=k(Mt-Mlim)_n where n=1 or 2, was obtained. When n=1, it became the first order equation dynamics equation; when n=2, it was the second order dynamics equation.