The traditional UHV grid reactive voltage regulation mostly starts from the point of suppressing voltage overshoot, which lacks comprehensive consideration of various information.In this paper, an optimal reactive voltage control method for UHV power grid based on improved analytic hierarchy process (AHP) is proposed.In this method.Three dimensional quantitative evaluation indexes such as voltage safety, reactive power exchange and line loss in UHV substations are constructed.Considering the optimization objectives from three aspects comprehensively, the comprehensive weight of reactive voltage regulation requirements of uhv substations is calculated by using analytic hierarchy process (AHP), and the optimization direction is determined.Through iterative solution, the global optimization strategy is obtained.Based on the actual data of north China power grid, the simulation results show the effectiveness and rationality of this method.