The simple harmonic vibration principle of the clamp rotation for manipulator was analyzed, and the corresponding relationship between the hammer displacement of radial forging machine and the intermittent rotation action of manipulator was summarized.A simulation model of the simple harmonic vibration system for radial forging machine was built by Amesim. Then, the functional relationship between the hammer displacement and the signal of simple harmonic vibration hydraulic control valve was established. Finally, the hammer displacement was converted into the control signal of hydraulic valve as three functional relationships: broken line, equal acceleration and deceleration curve and sine curve. The forging frequency was changed under the same conditions of other parameters, and the simple harmonic vibration effects achieved by the mentioned three functions were compared and analyzed. The results show that when forging at low frequency, the control effect is more satisfactory by using the equal acceleration and deceleration function curve signal to control hydraulic valve. As the forging frequency increases, the instantaneous pause time of the clamp is shorter, and the control effect is more satisfactory by using the sine curve signal to control hydraulic valve. When forging at high frequency, the rotation action of the clamp obviously lagged the control signal, and the relative angle of the displacement sensor of hammer and eccentric shaft, or the relative zero point of the displacement sensor needs to be adjusted accurately.