City gas has great safety hazards in the pipeline transportation process, and once the danger occurs, the consequences are unimaginable, so the monitoring and localization of gas pipeline leakage is of great significance. To solve the problems that most of the current pipeline leakage detection and localization methods are susceptible to environmental interference, low accuracy, narrow scope of application, and high computational difficulty, this paper proposes a weak fiber Bragg grating (wFBG) array pipeline leakage detection and localization technology based on time delay estimation, which collects vibration signals through wFBG technology. Based on the characteristis of the collected leakage viberation signals in the time and frequency domain, the method first detects whether the pipeline is leaking by the method based on short-time energy analysis, then performs polynomial fitting between the peaks for the signal fragments that meet the requirements to obtain the arrival time of the leakage information, and finally locates the leakage point according to the time difference. The experimental results show that the method can effectively detect leakage, and the localization error is about 1 m at a measurement distance of 40 m.