Abstract: Objective: Extraction of β-sitosterol from coix seed by ultrasound, and use to provide a reference for processing and utilization of functional food.Methods: In this experiment, coix seed was used as raw material and ground into powder, and the ratio of material to liquid, ultrasonic temperature, ultrasonic time and ethanol concentration were taken as single factor. The response surface method was used to study on the effects of different factors and their interactions on β-sitosterol extraction rate in coix seed.Results: The optimal extraction conditions of β-sitosterol in coix seed were as follows: liquid ratio ( methanol: coix seed) was 17.5∶ 1 m L/g, ultrasonic temperature was 52 ℃, ultrasonic time was 38 min.Under these conditions, the β-sitosterol average extraction rate was 8.93 mg/g close to the predicted value 8.97 mg/g in the model. Conclusion: The method had the advantages of simple operation, high yield and practical significance.