The existing leakage detection systems have challenges in identification and localization for pinhole leakage in long-distance gas transmission pipelines due to high costs and difficulty. This paper presents a model test for gas transmission pipeline leakage monitoring based on distributed acoustic sensing (DAS) technology. The optical sensing cable with a spiral structure effectively enhances the capability to identify leakage events. A method utilizing fast Fourier transform for pipeline leakage signal identification and precise localization is proposed. By analyzing the vibration of fiber in both time and frequency domains, the generation of leakage signals can be accurately detected. Preliminary localization of leakage points is achieved by observing the spectral average amplitude changes in each sensing channel. Additionally, a precise localization method based on cross-correlation algorithm is introduced, which improves the positioning accuracy of the optical sensing cable with a spiral structure from ~0.74 m to 0.24 m.