Considering the isolated power grid state changing between active power grid and passive power grid, an integrated control strategy is proposed for VSC station to supply power to isolated power grid. Based on the principle of VSC control, the difference of control modes of VSC-HVDC inverter in active and passive power grids is analysed. When isolated power grid changes from active power grid to passive power grid, the control mode of VSC station changes. Considering the stabilization of AC voltage and fast restoration of active power balance, two control strategies, angle following and active power priority, are proposed in the paper. A comprehensive control system is designed to ensure the minimum fluctuation of each electrical quantity of islanded power grid and DC system at the time of switching. The PSCAD/EMTDC simulation model of VSC-HVDC transmission system is established. The simulation results verify the validity of the integrated controller and control strategy proposed in this paper. The continuous and reliable power supply can be realized when the isolated grid state changes.