The feature of strong DC system and weak AC system in the CSPG becomes more obvious after Nuozhadu and Xiluodu HVDC system was put into operation. Transmission line fault, especially HVDC system block caused by lightning stroke fault impacts the safety and stability of power network for CSPG. This paper selects three typical lightning stroke fault which led to HVDC block in CSPG in 2013 to analyze response strategy of control and protection logic in different cases such as arc is not extinguished, dielectric strength is not restored, and transmission line is struck by lighting continuously. It points out the shortage of deionization time and the set time of fault counter. Finally, it suggests to avoid unnecessary HVDC system outage.