In order to optimize the ultrasonic extraction process of C. grandis osbecko seed oil, according to single-factor experiments, four independent variables, namely: the time of the ultrasonic-assisted extraction process, liquid ratio, ultrasonic power ratio and temperature, had been determined by RSM experiment. The results showed that, the optimal conditions were as follows: extraction solvent: isopropanol; extraction time 40.8 min; ultrasonic power ratio 73.77%; liquid ratio 5.9:1 (mL/g); extraction temperature 47.39℃. Under the optimum conditions, the extraction yield of C. grandis osbecko seed oil reached at 38.82%.