The invention relates to a coordination voltage control method of automatic voltage control between 500 kV of transformer substations, and belongs to the technical field of the automatic voltage control of the electric power system. The method comprises the following steps: within each control cycle T, calculating to obtain a sensitivity matrix of a power grid and a substation-to-substation coordination coefficient matrix; about each 500 kV of the transformer substation in the power grid which takes part in the automatic voltage control, forming a corresponding substation-to-substation coordination group of 500 kV of the transformer substations; according to the voltage out-of-limit situation and idle resource situation of each transformer substation in the substation-to-substation coordination group, calculating to generate a substation-to-substation coordination voltage control strategy by which the transformer substation assists the voltage regulation of other neighboring transformer substations. The method is used for adequately using an idle device configured in the power grid, eliminating the busbar voltage out-of-limit in the power grid, and improving the grid voltage stability and the voltage quality.