The invention discloses a safety control method and system for suppressing the continuous commutation failure of a DC system. The safety control system comprises a DC safety and stability control mainstation, a rectifier commutation control subsystem and an inverter side state detection subsystem. Based on a commutation failure mechanism, the DC power is dropped quickly by detecting the number ofcommutation failures of the DC system and the inverter side commutation bus voltage, so as to suppress continuous DC commutation failure. The risk of continuous commutation failure under a weak AC state of a receiving power grid can still be reduced. The continuous commutation failure of the DC system can be prevented, and the operation safety and stability of an AC-DC hybrid system can be improved.