The invention discloses a water supply pipeline leakage detection method based on a distributed optical fiber acoustic sensor. The method comprises the following steps that a laser emits pulse lasersto sensing optical fiber, the pulse lasers entering the optical fiber can generate weak rayleigh scattering at all positions in the transmission process of the sensing optical fiber, the sensing optical fiber is affected by external vibration to generate local strain changes, and phases of the rayleigh scattering light can be slightly changed. According to the method, leakage and external invasiondamage behavior of a water supply pipeline are detected and scanned, an alarm is raised within 10 seconds after an emergency occurs, the system can determine the accurate physical position of the event while the event is found, the precision is higher than +/-5meters, on the basis of deep learning, the system can automatically judge the property of the event and evaluate the degree of the event,so that a reliable technical basis is provided for subsequent adjustment, repair and replacement of the water supply pipeline.