The invention relates to a pipeline blockage monitoring system and a detection method thereof for blockage signals under strong interference. The system comprises a low-frequency sound wave emitting device arranged at the original/final station of a pipeline, a sensor array arranged at the original/final station of the pipeline, a data acquiring and preprocessing device with one input end connected to the sensor array, a blockage monitoring and positioning device connected to the output end of the data acquiring and preprocessing device and a monitoring terminal connected to the output end of the blockage monitoring and positioning device. By measuring the time delay between the emitted sound waves and reflected sound waves and combining the sound velocity in the pipeline, the position of a pipeline blockage point can be calculated accurately, and the system has the advantages of high positioning accuracy, high anti-interference ability, pipeline damage elimination, low false alarm rate, low missing rate, high fault tolerance and the like; when the blocking area is small or the interference is strong, the detecting and positioning abilities are improved greatly as compared with those of the single sensor method, and the system can be widely applied to pipeline monitoring in various fields.