Abstract: In order to explore and transport high viscous crude oil economically and effectively, the viscosity reduction experiment with different ultrasonic wave intensity, different ultrasonic wave frequency and different action time and the orthogonal experiments on dehydrated crude oil of the Shengli Shallow Sea Oilfield are carried out. And the optimum combination parameter of viscosity reduction with ultrasonic technique is gained. The results will help the ultrasonic technique apply in oil production and oil transportation.