At present, when the reactive power control function in HVDC project is required to select the voltage control mode because of the weaker AC system, or when reactive power control mode is in manual mode and the reactive power control function in DC operation is not equipped with the system reactive power balance control function, the problem of reactive power overstepping or insufficiency in AC system appears. This paper presents an optimization strategy of reactive power control function in HVDC transmission project, and verifies the feasibility of the optimization strategy through RTDS. This strategy has been applied for the first time in Gaolin Back-to-Back HVDC project, eliminating the problem of reactive power exceeding or insufficient while ensuring that the reactive power control function is manual mode or voltage control mode, and improving the stable operation efficiency of DC system. This work is supported by National Key Research and Development Program of China (No. 2016YFB0900600):“Control and Protection of Large-scale AC/DC Hybrid Interconnection Operation” and Science and Technology Project of State Grid Liaoning Overhaul Branch (No. 5222JX17006):“Research and Application of Group Manual Maintenance and Automatic Power Curve Function of SCADA System AC Filter”.