Abstract: A two-dimensional (2D) spatial location method of sound source based on phase sensitive optical time domain reflectometer (φ-OTDR) system was proposed. The method uses difference unwinding phase (DUP) method to extract the phase measured by sensing fiber. The phase demodulated by DUP method is smoother than that demodulated by UDP method, and DUP method can restore the time-domain signal of disturbance event with high fidelity, which solves the problem of signal distortion caused by the non-zero phase of the phase obtained by UDP method at the non disturbance point. This method was verified by sound source 2D positioning experiment, and the results show that the phase of DUP demodulation used for 2D location of sound source is basically consistent with the actual results. The error between the actual value and the real value is 0.09 m in X direction and 0.16 m in Y direction. The results show that this method can increase the utilization rate of phase information, improve the accuracy of sound source location, and has potential application value in pipeline safety monitoring, border security, intrusion alarm and other fields.