The mechanism and kinetics of parathion degradation was investigated under high frequency ultrasonic irradiation in aqueous solution. The pseudofirstorder kinetic model and the response surface methodology (RSM) were proposed to evaluate the effect of ultrasonic frequency, power and initial concentration on sonochemical degradation of parathion. With the response surface experiments and quadratic fitting model, it was clearly indicated that the quadratic model was significant (P=0.000 2) and the lace of fit was not significant (P=0.113 6). The R2 of the model was 0.973 3. Ultrasonic power, initial concentration and the square of ultrasonic frequency were significant items for the model. And it was also indicated that there was an optimal frequency for parathion degradation with the operating conditions and the degradation rate of parathion was found to decrease with increase of initial concentration and decrease of power.