The commutation failure is one of the most common faults in high voltage direct current transmission (HVDC) systems. In China, the control and protection system of ultra-high voltage direct current is provided with the logic of starting active DC blocking to avoid negative influence of continuous commutation failure. However, the possibility of DC blocking which is caused by the continuous commutation failure poses a certain threat to the safety and stability of operation in the power grid. The suppressing HVDC continuous commutation failure has received more attention by researchers around the world. However, the influence of harmonic on the HVDC continuous commutation failure has not been reported thoroughly yet. The method of commutation voltage-time area is applied to analyze commutation process for HVDC transmission, after which harmonic control parameters of additional control loop are obtained. In the recovery process, the influence of commutation failure on voltage dependent current order limiter is taken into account, and a method for reducing failure rate of HVDC continuous commutation with additional harmonic control is proposed. Finally, based on the CIGRE HVDC standard test system, the effectiveness of the proposed control method is verified by PSCAD/EMTDC.