Abstract: Based on theoretical analysis of doubly-fed induction generator and its vector control, and aimed at the two status of Variable Speed Constant Frequency(VSCF) wind power generation, the authors propose the control structure featuring a voltage outer-loop for no-load cut-in, and the structure featuring a power outer-loop for grid-connected generation. In accordance with the characteristics of wind power generation, a maximum power point tracking algorithm based on the variable step of the velocity to acquire the maximum wind power was developed. 110 kW VSCF doubly fed induction generator wind power system was constructed in the laboratory, which proved the validity and reliability of control strategy by research and analyses of results.