Velocity-loop control is widely used in the electro-optical tracking system for motor driving.Good velocity-loop response is helpful to improve the tracking accuracy of the electro-optical system.The motor of the system is driven by the Pulse Width Modulation (PWM) voltage outputted by the inverter.As the demand for accuracy and electro-magnetic compatibility of the electro-optical tracking system is increasing, inverter output filter must be used to suppress the electro-magnetic noises caused by PWM voltage.Traditionally,the design of the filter enhances electro-magnetic noise suppression based on the improvement of insertion loss,but the analysis of the impact of the filter on motor control is inadequate.To solve the problem,the influence of LC filter on the motor velocity-loop control is studied.The plant model of the motor with an LC filter is established,and the transfer function of the plant is given.A new design method of LC filter is proposed,which can reduce the influence on motor velocity-loop control as well as maintaining the insertion loss.Experiments on the velocity-loop control of electro-optical pod are conducted to verify the effectiveness of the proposed method.