Erosion phenomenon is quite common in petroleum industry, as one of the main mechanisms of material degradation, occurs frequently on high-pressure pipelines in hydraulic fracturing operation. With the increasing of operation times, the erosion and corrosion defects on the inner surface of the pipeline, would lead to serious material loss and equipment failure. In this paper a new type of test machine was developed to simulate the erosive wear behavior of metal materials caused by the multiphase fluid such as fracturing fluid, and study the erosion failure mechanism by various metal erosion influencing factors including the velocity of multiphase flow, solid particles of fracturing proppant and impact angles, etc. The erosion-wear experiments on 20CrNiMo steels used in high-pressure pipelines is described in detail. Finally, the microcosmic surface testing was also used to analyze the erosion failure mechanism of metal materials for high pressure pipelines.