The mustard seeds were used as material and extraction rate of isothiocyanate was taken as the reference index. Three single factor experiments, ultrasonic temperature(40, 50, 60, 70, 80 ℃), ultrasonic time(20, 30, 40, 50, 60 min) and ethanol volume fraction(65%, 75%, 85%, 95%, 100%) , were designed to extract the effective components of mustard seed. And then the response surface analysis was carried out on the basis of single factor tests to explore the best extraction process of effective components of mustard seed. The results showed that the extraction rate of isothiocyanate was highest (2.199%) while 70% volume fraction of ethanol was used as extraction solvent in ultrasonic extraction, with 50 ℃ultrasonic temperature and 40 min ultrasonic time.