The invention discloses a method of suppressing DC commutation failure based on a VDCOL additional controller, which comprises the VDCOL additional controller and a VDCOL controller. The method comprises the following steps: the VDCOL additional controller calculates reactive power outputted by a STATCOM to obtain an additional current instruction; the VDCOL controller calculates the DC voltage toobtain a first current instruction; and the first current instruction and the additional current instruction are calculated to obtain a DC instruction. In the method, the second current instruction is a fixed value in a certain interval, the second current instruction can be adjusted according to the reactive power outputted by the STATCOM, and the output of the second DC can be controlled by combining the reactive power of the system and the DC voltage, so that the oscillation of the AC voltage is effectively inhibited, and the occurrence of continuous commutation failure is prevented.