Abstract: The large-scale development of offshore wind power makes the system prone to sub-synchronous oscillations under abnormal operating conditions, and the rapid voltage fluctuations may cause continuous commutation failure. In this paper, we analyze the mechanism of this phenomenon and effectively suppress the sub-synchronous oscillations by optimizing the control method of doubly fed induction generator (DFIG). At the same time, the multi-infeed interaction factor (MIIF) of each DC dropout point is associated with the difference in the regulation ability of wind farms in different regions to fully mobilize the compensation ability of wind farms in different regions to raise the system voltage. This method effectively suppresses the failure of off-site continuous commutation failure in the DC multi-infeed system. Finally, the effectiveness of the proposed strategy is verified by PSCAD simulation comparison.