Abstract: The sound field of direct zone in deep waterhas obvious multi-path structure, which can be used for passive localization of underwater sound source. Using the data obtained from an experiment in the South China Sea, a combined source localization method for underwater target in deep water is proposed, whichestimates the range based onthe cross-correlation function of signals received bytwovertical hydrophonesand depth from the autocorrelation function of signals received bya single hydrophone. Firstly, the arrival time of the direct wave is extractedfrom the cross-correlation function to estimate the source rangeby assuming the source depth range from 50m to 300m. Then, the delay time between direct wave and surface reflect wave is extracted from the auto-correlation function of one receiver to estimate the sound source depthcombiningthe range estimationresult.Finally, a more accurate range estimation can be derived by combing the average value of the depth estimation result and the cross-correlation function. The results show that the relative error of range estimation is within 10.5%, and the relative error of sound source depth estimation is within 13.3%.