The current controller with fast transient response and satisfactory steady state characteristics is required in PMSM Servo System. In this paper, the application of active disturbance rejection control (ADRC) for current loop is proposed and the design proceeding of a first-order ADRC controller in the current loop is elaborated. Then, by taking use of the ADRC controller and the analysis of the digital control delay effect, an improved method focusing on delay effects is presented. By taking these measures, the current regulation can achieve high performance. Simulation and experimental results verify the correctness and feasibility of the proposed method.