Fault location of DC distribution network is the key to fault diagnosis, line safety and power supply quality. This paper firstly studied the fault location techniques in DC micro-grid, and then, based on the voltage source inverter DC micro-grid, the failure response features of the single-electrode fault and inter-electrode short-circuit fault were analyzed, finally, a new method was proposed to determine the fault location by extracting the circuit inductance value of fault voltage and current information from converter outlet side capacitance discharge process, The fault process is segmented according to the voltage relationship, and the fault line selection is carried out by using the change rate of transient current. Finally, the fault location is determined according to the second-order response process of the fault circuit. Simulation results in PSCAD/EMTDC show that the location algorithm can accurately identify fault types and fault lines and locate the fault location. The positioning error of inter-electrode short-circuit fault is within 0.5% and that of single-electrode grounding fault is within 3%.