In order to realize the performance of motor, the influence of torque pulsation by different number of slider was studied based on the analysis of the theoretical displacement and theoretical torque of double-stator single-acting multi-motors. Through the analysis, mathematical expressions of the motors torque and the number of sliders were obtained. Meanwhile, the results show that lag angle could influence torque pulsation when outer motor and inner motor work at the same time and differential connections. This research work laid a theoretical foundation for the design of double-stator single-acting multi-motors. 