The single safety coefficient method is used to calculate the anti-overturning stability and safety of hydraulic retaining wall in the current specification，without pointing out whether water pressure is an overturning force or a stability force. Aiming at the problem that the different calculation methods of water pressure have a great influence on the anti-overturning stability and safety coefficient，according to the calculation principle of single safety coefficient method，this paper compares the calculation results of the specification method and commonly used design software by specific computation example，and obtains the suggested formula. The results show that in order to make the calculated anti-overturning safety coefficient truly conform to the engineering safety level，it should regard the difference between the horizontal water pressure on both sides of the retaining wall and basement seepage pressure as the load，and weight of the retaining wall calculated by buoyant density below the water level in front of the wall as the resistance force.