Aiming at the key technical problems encountered by domestic and foreign scholars in building the real-time monitoring system for the micro leak of three-dimensional pipe networks, the paper classifies the problems into three aspects: 1) in the extraction of fault signal frequency, how to avoid the effect of the mixed echo stack and improve the delay estimation accuracy of the correlation; 2) in network bifurcation structure, how to discern the signal propagation path, and how to locate the leak source; 3) under the uncertainly delay in transmitting and receiving information data, how to ensure the time synchronization accuracy of the real-time monitoring system for the three-dimensional pipe network leakage. Through the comparison of the monitoring technologies for the pipe network leakage at home and abroad, it shows that the acoustic emission sensor network based three-dimensional pipeline leak real-time monitoring has great advantages in detecting the weak leakage of flammable and explosive gas/liquid transportation pipelines.