Abstract: Cold pressed prickly ash cake was used as a raw material, the ultrasonic and ethanol technology was adopted to extract the oil in the cake.Indicators were the grease yield, the solid- liquid ratio, ethanol concentration, ultrasonic power, ultrasonic time and ultrasonic temperature were used to study the effect for oil extraction.Base on the single factor experiments, a three- factor- three- level experiment design had been developed. The results indicated that the optimum conditions of extracting the residual Zanthoxylum oil were as follows: solid- liquid ratio was 1∶15 ( m∶ V) , ethanol concentration was 90%, ultrasonic power was 240 W, ultrasonic time was 50 min, ultrasonic temperature was 70℃, the maximum yield of residual Zanthoxylum oil was 5.82%, and does not change the quality of oil.