The commutation failure of a single HVDC can easily lead to the simultaneous commutation failure of its neighboring HVDCs, which in severe cases will cause HVDC blocking and chain failures. An online warning method for multi-infeed HVDC commutation failure based on the prediction of the commutation voltage-time integration area is proposed. First, by analyzing the AC voltage and DC current dynamics during the HVDC commutation process, real-time prediction of the commutation voltage-time integration area is achieved. Second, a HVDC transmission commutation failure warning factor is derived from a single HVDC system to a multi-infeed HVDC system based on the aforementioned prediction method. Then the main parameters of this factor are determined. Third, the application of this coefficient is illustrated by introducing it into the commutation failure prevention control. Finally, the correctness of the proposed warning coefficients for HVDC commutation failure and the guidance for commutation failure prevention are verified in the PSCAD/EMTDC platform based on the CIGRE HVDC model and the multi-infeed model.