In the application of traditional sliding mode control in three-phase voltage-source PWM rectifiers, the inherent discontinuous switching characteristics lead to high-frequency oscillations on the DC bus voltage, making it difficult to achieve ideal control performance. Therefore, a dual-loop control strategy that integrates outer-loop Fast Terminal Dynamic Sliding Mode Control and inner-loop feedforward-decoupled PI control is proposed in this paper. Firstly, inner loop employs feedforward decoupling-based PI control to eliminate the coupling terms in the mathematical model and achieve precise tracking of the current waveform. Secondly, the outer loop transfers the switching term to a higher-order differential element and introduces a fast terminal sliding surface design to suppress system chattering, enhance dynamic performance, and ultimately achieve accurate and stable tracking of the reference voltage. The stability of the controller is proved by Lyapunov stability theory, and experimental validation is conducted through simulations using Simulink. The results demonstrate that the proposed strategy effectively suppresses the inherent chattering phenomenon in sliding mode control. During system startup, the DC voltage overshoot is merely 6.5 V, with the peak voltage deviation reduced by over 92% and the settling time shortened by 91% compared to PI control. Voltage step-response tracking completes within 0.02 s. while transient voltage error remains bounded within ±1% under ±50% rated load disturbances. This control method ensures high steady-state accuracy while maintaining excellent dynamic response performance.