For the problem that it is difficult to find and locate the leakage or the blockage of the pipelines buried in the soil, combined with fiber optic pressure sensor with high sensitivity, high anti-jamming feature, a pipeline monitoring system was designed based on fiber optic pressure sensor. It used polarimetric pressure sensor which consisted of single mode fiber optic coated with a suitable thermal expansion coefficient of the material to overcome ambient temperature perturbation well. The pressure sensitive probes with modular design were distributed in pipeline every 20 meters to form an array of source signal point. Combined with lattice array data reconstruction and "interpolation positioning algorithm" to determine the location of faults. The results indicate that the system of fiber optic pressure sensor can effectively overcome the adverse effects of temperature changes on the sensor measurement. Within the range of 5.5 km, the positioning accuracy of fault point is within ±1 m.