Abstract: For optimal parameters of extraction condition for oxymatrine of Sophorae tonkinesis, effects of ultrasonic extraction time, ultrasonic extraction temperature, et al. on oxymatrine yield were studied through single factor experiments and orthogonal experiments. The results indicate that the effect sequence of four main factors for oxymatrine yield are as follows: ultrasonic extraction time, ultrasonic extraction temperature, ultrasonic power, immersion time. The optimal extraction conditions are as follows: ultrasonic extraction time 150 min, ultrasonic extraction temperature 90℃, ultrasonic power 300W and immersion time 20 min. Oxymatrine yield of Sophorae tonkinesis under the optimal extract conditions is 1.253%. Compared with control experiment, oxymatrine yield and oxymatrine content in extract are increased by 73% and 17%, respectively.