In order to improve the control effect of UHV AC grid bus voltage, given the current status of UHV grid construction, the influence of line power flow fluctuation on bus voltage is analyzed, and a control strategy is proposed which has the ultimate goal of weakening the power flow fluctuations on the UHV bus voltage and assessing the minimum difference between the actual value of the voltage control and the target value and taking the maximum system dynamic reactive power reserve increment as the objective function. Examining the effect of line reactive power flow on bus voltage, the reactive power sensitivity coefficient between substations is introduced in the objective function to reduce the reactive power flow between substations. The actual grid simulation results show that the proposed control strategy can effectively improve the voltage regulation effect and reduce the output capacity of dynamic reactive power compensation. This work is supported by the National Natural Science Foundation of China (No. 51907114).