In a permanent magnet synchronous motor (PMSM) vector control system, a proportional-integral (PI) regulator is generally used for implementing closed-loop current control in the synchronous rotating coordinate system. In this algorithm, a rotating coordinate transformation is necessary for both stator current and reference voltage commands, resulting in relatively high computational complexity. With reference to the design principle of traditional PI current regulators, a reduced-order resonant current controller was developed in this study. This controller only involves a single-time rotating coordinate transformation of the reference current command, thus significantly reducing the computational workload. In addition, to facilitate the practical application, a gain-parameter analytical calculation formula applied in the design of the resonant current regulator is presented in this paper. Given accurate model parameters, the proposed resonant current regulator exhibits a dynamic performance similar to that of a traditional PI current regulator. In addition, with the presence of parameter errors, this resonant current regulator exhibits superior decoupling control performance. The effectiveness and feasibility of the proposed regulator have been verified with the simulation and experimental test results.