The invention pertains to the pipeline monitoring technology, particularly a fiber pipeline monitoring system. The system is composed of an optical transmitter module, an optical interferometer module, a monitoring line, a modulator module, an optical receiver module and a signal processing module. The system can get two signals corresponding to different optical path positions of the same vibration though multiplexing a fiber interference system, compare the spectrum characteristics of the two signals, and eliminate the interference of the position information caused by the vibration information so as to obtain the accurate vibration position information under the condition that the system adds no photoelectric detector. The position information is obtained through the medium value of the spectrum amplitude ratio of the two signals, and the difference caused by the instability of the detection signal is eliminated, thus the accuracy of the location is greatly improved. The location function is realized with single-core fiber under the condition of not constituting a loop, thus the location monitoring can be realized by paving equal-distance main line along the petroleum pipe line, which has strong environmental applicability.