To cover the shortage of dynamic reactive power of the weak system in ±500 kV Yong-Fu HVDC Project, three sets of 100 Mvar-level STATCOM devices installed at Funing Converter Station. In this paper, the control strategy and response characteristics of STATCOM are explained in detail by analyzing the reverse control of STATCOM during AC filter input and transient support in AC instantaneous fault recovery. The problems of the STATCOM transient blocking and exit are analyzed by STATCOM's characteristics which are verified by collating STATCOM design research and field test data, and the STATCOM trip event caused by the artificial alternating current short circuit test of "01.10" in Funing Converter Station. This paper reveals the operational characteristics of large-capacity STATCOM devices in DC converter stations. Through the coordination and transient control of STATCOM, the risks of DC commutation failures and disturbances are reduced, and STATCOM control strategy optimization measures are proposed. By studying the response characteristics of STATCOM in Funing Converter Station, it has been proved that three sets of STATCOM provide support for the stable operation of the DC system at Funing Converter Station. This work is supported by National Natural Science Foundation of China (No. 51707026) and National Key Research and Development Program of China (No. 2016YFB0900200).