Abstract: In order to improve the capacity of existing pipeline leak monitoring system based on negative pressure wave to detect slow pipeline leak, the upstream and downstream pressures of the pipeline were analyzed by identifying the pressure decline trend on the basis of leak monitoring technology based on negative pressure wave. Then, pipeline leak was identified by detecting the continuous pressure decline. Different from common leak monitoring technology based on negative pressure wave, the pressure decline trend detection method doesn't need to set the detection threshold when it is used for leak identification, and it can detect and identify fast and slow pipeline leak by adjusting the length of calculation data. Finally, the method was compared with which sets detection threshold by means of on-site oil release test. It is indicated from the test results that pressure decline trend detection method can increase the sensitivity of the leak detection technology based on negative pressure wave.