Abstract: This paper proposeds a novel design method of AC motor current regulator in discrete-time domain, which belongs to the high-performance control field of AC motor drives. In FOC, the linear PI regulators are used to design the d-axis and q-axis current loops. Due to the influence of the cross coupling term, the discrete error of the controller and the delay of the digital control system, the control effect of the controller is degraded. Therefore, this paper proposed a novel method where the d-axis and q-axis current loops are considered as a whole. Then, the current loop model of AC motor is established in the discrete-time domain. At the same time one step delay is considered in digital system to design discrete-time current regulator. Finally, based on the automatic control theory, the maximum and optimal value of current regulator parameters are derived.