To improve the frequency response performance of wind energy conversion system (WECS), an adaptive virtual synchronous generator (AVSG) control method is proposed in this paper. Different from the constant virtual inertia parameter configuration of conventional WECS with VSG control (WECS-VSG), the virtual inertia parameter of the WECS with AVSG control (WECS-AVSG) is adjusted according to the rate of change of frequency (RoCoF) at the first beginning of inertial response stage. When the power imbalance of the power system is small, the practical virtual inertia of WECS-AVSG can automatically increase and then the WECS-AVSG can provide more support to the grid frequency response than conventional WECS-VSG. The simulation results show that the frequency response of WECS-AVSG is better than that of WECS-VSG under the same power disturbance condition.