This paper investigates the modeling and decoupling control of grid-connected voltage source inverter (GC-VSI) for wind energy conversion system (WECS) applications. Firstly, the typical configuration and operation principle of the direct-driven grid-connected WECS are analyzed. Then, by means of input-output modeling method and instantaneous active power theory, a time domain mathematical model of the GC-VSI is set up. Besides, in order to resolve the GC-VSI active current and reactive current cross-coupling nonlinear control problem, a vector decoupling control method for the GC-VSI firing pulse generation is deduced in the dq synchronous rotating coordinates. The proposed decoupling control method can realize the active power and reactive power of the GC-VSI injected into the grid are regulated independently. Finally, the performance of the proposed GC-VSI system is evaluated by using MATLAB/Simulink simulation.