The work aims to optimize the extraction condition for total saponins from Rosa sterilis by ultrasonic-assisted method, so as to improve the extraction efficiency. The effects of ethanol volume fraction, ultrasonic time, material-liquid ratio, and extraction number on the extraction yield of total saponins were investigated by single factor experiment method, and then the central composite design of response surface methodology was carried out to determine the optimum extraction conditions. The optimal extraction conditions were defined as ultrasonic time of 40 min, ethanol volume fraction of 60%, material-liquid ratio of 1∶30 g/mL, and extraction number of 4 times. Under these optimal conditions, the actual extraction yield of total saponins was 9.15%, which was almost equal to the predicted value of 9.18%. These results indicated that the response surface methodology was feasible to optimize the ultrasonic-assisted extraction conditions of total saponins from Rosa sterilis. The work provides reference for the exploitation and utilization of Rosa sterilis in food preservation and medicine.