Abstract: After the AC side short-circuit fault occurs in a multi-infeed DC system, the voltage of the AC system will continue to decrease, and will thus cause the commutation failure of multiple or even simultaneous failure of all DCs, which will seriously damage the security and stability of the power grid. The synchronous condenser has overload capability, and its reactive output is negligibly affected by the system voltage. The voltage drop caused by the AC fault can provide strong reactive power support, and can thereby suppress the occurrence of DC commutation failure. To suppress the failure of DC commutation, a synchronous condenser optimization configuration method for suppressing multi-feed DC commutation failure was proposed, which was optimized for both installation location and capacity. Firstly, starting from the duration of DC commutation failure, and taking the interaction between DCs into account, we proposed an effective index for suppressing commutation failure. Then, according to the electrical distance, the area to be selected was determined, and the best compensation location of synchronous condenser was selected by the reactive compensation response index.Thirdly, the configuration optimization model of synchronous condenser was established, and the optimal configuration scheme was solved in two stages to obtain the final configuration scheme. Finally, the actual large-grid simulation results show that the final solution can effectively suppress the multi-feed DC commutation failure caused by AC fault while considering economy.