Erosion–corrosion is the main cause of pipeline failures, especially in pipe bends, plugged tees, and pipe fittings with different cross sections. In this study, the erosion of a stressed pipe bend (arising from the internal high-pressure fluid) caused by particles entrained in the conveying fluid was investigated based on a numerical analysis. A numerical model based on the authors’ previous work was combined with a new erosion equation that considers the effect of the tensile load on erosion to analyze the erosion mechanism of a pipe bend under high pressure. The numerical model was verified by the erosion test of API X65 pipeline steel, and a systematic parametric study was also carried out. Moreover, a new numerical simulation method that considers the surface scar evolution of a pipe bend based on the erosion history, was proposed. This work provides an alternative means of understanding erosion behavior and predicting erosion damage of in-service, highly stressed oil and gas pipelines.