As a key actuator in a flight control system, the performance of an electromechanical actuator has a significant impact on the dynamic responses of the system. Based on the structural composition of the directdrive electromechanical actuator, a simulation model is established that considering the control of a permanent magnet synchronous motor and nonlinear factors of a planetary roller screw mechanism. The step responses of the system under the current vector control of “id=0” are studied. The results show that the system based on the threeclosedloop servo control strategy of the PMSM has the good dynamic performance under different position commands with the step signal. With the comparison to the literature, it is shown that the proposed simulation model of the electromechanical actuator under this control strategy is effective.