A distributed static series compensator (DSSC) can change the power of a transmission line by adjusting the voltage injected into the line to optimize the power flow distribution of the power grid. In response to the problem that existing AC line protection algorithms are difficult to adapt to the operation of a DSSC, a method to suppress the influence of the DSSC on line protection is proposed. First, the impact of a DSSC on AC line protection is analyzed, and it is proved that the injection voltage of the DSSC may change the impedance measurement value of distance protection, leading to the risk of the protection rejecting or mis-operating. Then, a method to quickly bypass the DSSC using the overcurrent protection of the DSSC, or to actively reduce the injection voltage of the DSSC to 0 based on fault auxiliary criteria is proposed. This is to suppress the impact of the DSSC on line protection during different types of line faults. Finally, based on the hardware-in-the-loop RTDS real-time simulation platform and on-site testing of the Zhejiang Huzhou DSSC demonstration project, the effectiveness of the proposed method is verified.