Doubly-fed induction generator (DFIG) is widely adopted in the current field of variable speed and constant frequency wind power generation technology, which is ultimately converted into electricity that meets grid connection standards through inverters and variable speed devices. However, the wind energy resources vary randomly. Therefore, establishing the mathematical models of wind power generation system, analyzing its operating characteristics and formulating corresponding optimal control strategies, are of great theoretical and practical significance for ensuring power quality and improving power generation efficiency of DFIG system. Firstly, this paper analyzes the basic structure of the inverter used in DFIG and derives its mathematical expression. Then, an optimal vector decoupling control is proposed, which includes a voltage and current control scheme for grid-side converters and a decoupling control method for real and reactive power of rotor-side converters. The former is used to achieve constant DC bus voltage, while the latter is used to achieve maximum wind energy capture. Finally, a closed control loop is conducted under the software of MATLAB/Simulink to examine the validity of the designed control scheme. The simulation results demonstrate that our proposed optimal control scheme can well track the maximum power point under random disturbances.