To improve the simulation and judgment accuracy of leakage in pipeline systems, two distinct unsteady friction models, including the Brunone model of the transient acceleration type and the weighting function type(Zielke and Vardy models), were introduced to simulate the hydraulic transient leakage, and the results were compared with the experimental and simulation data in the published papers for further analyses. The calculated results show that Zielke model and Vardy model can simulate the pressure and flow signal changes more accurately compared with traditional friction models and the Brunone model due to simplification errors. The leakage leads to the distortion of pressure and flow because of new signal reflection caused by the leakage in the pipeline. Both the leakage discharge and position affect the degree of distortion, amplitude and attenuation of the transient pressure and the flow in the pipeline.