Abstract: With the current large-scale new energy is connected to the grid,in order to solve the problems that the voltage stability margin of the AC/DC power grid is greatly reduced and the voltage stability control capability of the UHV DC system is insufficient,the dynamic reactive power allocation strategy for UHV system with a large amount of new energy is presented. Then a dynamic reactive power allocation strategy based on quantum genetic algorithm is proposed. Firstly,the sensitivity analysis of the AC-DC hybrid system is carried out,and a dynamic reactive power allocation evaluation index considering the steady and transient processes is determined.Then a dynamic reactive power allocation optimization model of UHV new energy system based on this index is established to realize dynamic reactive power optimization. At last,the proposed strategy is applied to the actual power grid,and the practicality and effectiveness of the strategy are proved by calculation.