For the DC side bipolar short-circuit fault, firstly, the impact to DC side power and capacitor charging after locking is analyzed, and then the suggestion for reducing the impact of fault on the AC side reactive power is proposed. For the DC side monopole ground fault, simulation results show the impact that the stability of the system is connected with the values of the grounding resistors, and suggestion is proposed in grounding resistor choice. For the DC side disconnection fault, it draws a conclusion for the stability of the system in different control modes. In addition, the impact of the locking time on the system is analyzed. Finally, the correctness of the above analysis is verified by the simulation of a single ended and double ends half bridge sub-module DC converter system in PSCAD/EMTDC. This work is supported by National Natural Science Foundation of China (No. 51277068), and Program for New Century Excellent Talents in University (No. NCET-12-0846), “111” Project of China (No. B08013), and National High-tech R & D Program of China (863 Program) (No. 2015AA050101).