The invention relates to a experimental system for scientific research, in particular to a pipeline leakage detecting and positioning experimental system and a detection method thereof, and the system is used for realizing detection and positioning experiments on leakage of long-distance gas conveying pipelines and long-distance liquid conveying pipelines by virtue of different leakage detection methods. The pipeline leakage detecting and positioning experimental system comprises a conveying pipeline, a medium conveying device, a negative-pressure wave detection device and an acoustic emission detection device; the medium conveying device comprises a conveying pipeline, a medium container, a surge tank, a water pump, an oil pump, a water tank outlet flowmeter, a water tank inlet flowmeter, an oil tank outlet flowmeter, an oil tank inlet flowmeter, a nitrogen cylinder outlet valve, a water tank outlet valve and an oil tank outlet valve; a bent part of the conveying pipeline is of a U-shaped pipeline, and the rest part of the conveying pipeline is a straight pipeline section; the negative-pressure detection device comprises a pressure sensor, an electromagnetic flowmeter, a data acquisition card and a computer; the acoustic emission detection device comprises an acoustic emission sensor, a signal preamplifier, an acoustic emission detection instrument and a computer; the acoustic emission detection instrument is used for processing signals, and transmitting the signals to the computer of the acoustic emission detection instrument so as to analyze the signals.