The invention discloses a reactive voltage optimal control method for wind electricity and photo-electricity integrated grid connection and belongs to the technical field of wind electricity and photo-electricity grid connection control. The reactive voltage optimal control method includes that execution stations used for respectively controlling wind electricity plants/photo-electricity plants one by one, secondary stations used for controlling the execution stations and a primary station used for controlling all the secondary stations are arranged; the primary station calculates preset voltage reference value Uref of each secondary station; the preset voltage reference values Uref are processed in a 3 sigma method to obtain a preset voltage reference value interval; high voltage side bus voltage of the secondary stations is adjusted to be within the preset voltage reference value interval; and if the high voltage side bus voltage of the secondary stations is not in the preset voltage reference value interval, devices in the wind electricity plants/photo-electricity plants are adjusted through the execution stations. The reactive voltage optimal control method provides guidance for the power systems in practical operation.