Degradation of acephate pesticide by ultrasonic wave was studied.The effects of ultrasonic power,time,pH value of solution,initial concentration of solution and nanometer TiO2 on the degradation of acephate pesticide were investigated.the results indicated that the degradation rate of acephate increased obviously with the increase of ultrasonic power and time.pH values of the solution also exhibited significant influence,both acidity and basicity condition were favor for the degradation.Nano-TiO2 enhanced the degradation of acephate as well.The degradation ratio of acephate pesticide surpassed 85% within 1h under the condition of: ultrasonic frequency of 25 kHz,output power of 60 W/cm2,1.0 g/L Nano-TiO2 catalyst,pH of 2.5,and temperature of 25℃.