Abstract: The ultrasonic- assisted extraction process of seed oil from Perilla frutescens was optimized by the design of Box- Behnken on the basis of single factor experiment with the reference of oil yield.Results showed that sample- to- solvent ratio,ultrasonic temperature and ultrasonic time had significant effects on extraction rate and the order was ultrasonic time > sample- to- solvent ratio > ultrasonic temperature. The optimum conditions were sample- to- solvent ratio of 1∶ 18,ultrasonic temperature of 58 ℃ and ultrasonic time of 80 min. The extraction rate was up to 43.57% under this condition.There were eleven fatty acids in the oil and the unsaturated fatty acids were up to 90.54%.The content of 9,12,15- octadecatrienoic acid was 201.56 mg / g dry weight seed,which was 61.17%of the total fatty acids. The iodine number,acid value,saponification value,peroxide value of the seed oil were185.00 g /100 g,2.00 mg / g,181.81 mg / g and 1.93 mmol / kg,respectively,which indicated that the extracted seed oil from Perilla frutescens had perfectly edible quality because it was not easy to be oxidized and rancidified.