Variable-step Hill Climbing Searching (HCS) can realize Maximum Power Point Tracking (MPPT) of Doubly-Fed Induction Generator (DFIG) wind power generation system without measuring the wind velocity or obtaining the wind turbine’s power-speed curve, and has a brilliant future. This paper firstly proposes a wind turbine imitation method based on its operation characteristics. Then, a DFIG MPPT control strategy based on variable-step HCS is presented. Then the method is applied to the DFIG vector control strategy directed by stator voltage. At last, an experiment platform with DC simulation machine is built. The experiment results show that the proposed variable-step HCS can not only search the optimum speed automatically and realize MPPT, but also has the ability of responding to the polytropic wind. The feasibility and effectiveness of proposed control strategy are validated.