Abstract: In order to increase extraction yield of soybean dreg protein,the synergistic extraction experiment of soybean dreg by ultrasonic/microwave was executed. The effects of ultrasonic power,ultrasonic time,microwave power,microwave time,solvent-to-material ratio and p H on protein extraction yield were discussed. On the basis of single-factor experiments,the process conditions were optimized using orthogonal test. The results showed that the synergistic extraction by ultrasonic/microwave was a feasible method for the extraction of soybean dreg protein. The best process conditions were as follows :ultrasonic time 30 min,microwave time5 min,solvent-to-material ratio 10.30∶1,p H9.5,microwave 440 W and ultrasonic 400 W. In this process conditions,the extraction yield of dreg protein could reach about 94.14%. And the actual value of the extraction yield was93.43% and was in good agreement with the predicted value. The obtained protein molecular weight was between 13.427×103~338.96×103u. The protein exhibited homogeneous texture,good sensory quality.