A fully-distributed reactive voltage control method, includes: establishing a power grid reactive voltage optimization model of a power grid; parting the power grid reactive voltage optimization model into a plurality of area reactive voltage optimization models of a plurality of areas of the power grid; converting a power flow equation constraint in each of the plurality of area reactive voltage optimization models to a linear regression model; solving the linear regression model by using a robust recursive regression algorithm to obtain a solution result of the linear regression model; solving each of the plurality of area reactive voltage optimization models by using the solution result of the linear regression model, a gradient projection algorithm, and an alternating direction multiplier algorithm, so as to realize a reactive voltage optimization control of each of the plurality of areas.