Abstract: A new kind of continuous revolving electrohydraulic servo cam rotor motor on the nonmagnetic simulation turntable was introduced with its operating principle and features. The mechanism of the motor’s torque fluctuation was found based on the systematical force analysis of motor’s vanes. The simulation of disturbing torque produced by the vane was emulated by using the matlab software when the servomotor is working under the lowspeed. From the comparisons of disturbing torque under different oil pressure on the reducing valve or different vane thickness, the related parameters’ effect on the torque fluctuation of this kind servomotor was revealed. The work in this paper presents some theory basis to resolve the phenomenon of velocity fluctuation with lowspeed of the servomotor.