With the technical requirements of ultra-high voltage（UHV）power grid for the automatic voltage control（AVC）system，the adaptability of current control methods for AVC system is analyzed.After adjusting the traditional reactive voltage control strategy using economic voltage difference，the multi-level coordinated AVC control strategy for UHV power grid is proposed and its effectiveness and feasibility are proved by actual grid digital simulation.Its implementation can assure the reactive power hierarchical balance in real time between UHV grid and500kV grid.The grid loss can be significantly reduced and the economic benefit of the grid operation is increased.Meanwhile，the effective integration between the AVC system of the UHV grid and the provincial power grid AVC system is achieved，and the upgrading work on the existing AVC system of provincial grids can be reduced as much as possible to save the investment.