Because of the diversity and space-time discretion of DC converter faults， it is very complex to do the fault analysis and protection coordination. With current methods the relationship of protection and fault is not one-to-one. The same fault may lead to different protection actions，also it is not effective to do the fault location analysis from the protection action. Combining the simulation results of the CIGRE HVDC benchmark system， this paper analyses 7 typical grounding faults at the HVDC conversion. The difference of converter operating conditions and electrical characteristics caused by different fault locations is identified. Based on the influence of the fault time on electrical characteristics， a method for dividing fault feature stages is proposed. Finally， combined with the time characteristics of valve， a new discriminant method for fault location with the cooperation of electrical characteristics and delay is proposed.