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On the premise of no additional investment in hardware equipment, it is of great significance to improve the ability of the DC transmission system to suppress continuous commutation failures. To this end, firstly, the commutation mechanism of HVDC transmission system based on grid commutation is expounded, the control method of VDCOL is analyzed, and the voltage dependent current order limiter (VDCOL) is activated according to the real-time measurement of the commutation bus voltage. The starting voltage of the system replaces the conventional DC voltage measurement to obtain the starting voltage that changes slowly during system faults. Secondly, based on the analysis of the normal switching mechanism, the linear static recovery relationship between the DC voltage and the DC current of the conventional VDCOL is changed, the conventional control model of the VDCOL is replaced with a variable slope mathematical model, and the calculated VDCOL start-up voltage is combined with the variable slope VDCOL. Finally, based on the CIGRE HVDC standard test model, it is verified that the control strategy proposed in this paper has obvious effectiveness and superiority in suppressing continuous commutation failure.