The rapidity and overshoot of traditional PI control systems are often not met simultaneously; on the other hand, the effect cannot meet expectations in situations with high dynamic performance requirements. Therefore, the fractional order control method was studied, and the fractional order PIλ control was introduced on the basis of the internal model decoupled control system. Then the fractional speed loop control was designed. At last, simulation results show that the fractional-order controller has obvious advantages in dynamic performance, disturbance rejection, and robustness compared with the traditional PI controller.