Preliminary investigation for pipeline safety real-time monitoring with distributed fiber optic sensing technique based on coherent Rayleigh backscattering was carried out. On the basis of a novel one-dimensional impulse-response model of coherent Rayleigh backscattering in fiber, the influence of backscattering power curve with multiple continuous input pulses under external disturbance was explained. Coherent Rayleigh backscattering light power curve was visually presented through numerical simulations with the theoretical model. In order to demonstrate the model, an experimental measurement with 4 km-long single-mode sensing fiber was performed and the position where the disturbance occurs was easily found. To improve the SNR, a normalization method of peak-seeking with software was introduced. This method can effectively reduce average number and enhance the maximum detectable frequency range of external disturbance.