This paper presents a model predictive control (MPC) method, which allows EVs to participate in the grid voltage regulation as a reactive power compensation device to maintain the grid voltage within a stable range while keeping EVs charged to the desired state. According to the number of the connected EVs, the EVs can assist or even replace the traditional reactive power compensation device to achieve control objectives. The proposed method uses a two-stage hierarchical control scheme based on model predictive control to minimize the deviation of voltage profile while satisfying system constraints. The applicability of the proposed method is verified through a 19-bus radial distribution system. Simulation results show that based on the proposed scheme, EVs can assist or replace traditional reactive power compensation devices to participate in grid voltage regulation and achieve better voltage control performance.