The maximum value of the absolute value of the fourlayer wavelet coefficient can be used to distinguish the DC fault and the AC fault. By modeling the HVDC system, several common faults are illustrated and simulated using the MATLAB wavelet toolbox. The fault types are identified by observing the discrete wavelet analysis of the 4layer reverse traveling wave voltage during different faults, and the DC faults and AC fault types are distinguished. Simulation results show the practicability of wavelet transform.