Abstract: The fluid-solid-heat coupling equation established is used to analyze the flow field, stress and strain of multiphase medium flowing throughout the pipeline elbow via the Fluent and Ansys software, and further research on the influence of different inlet velocity, pipe diameter, R/D-ratio and liquid temperature on elbow erosion failure is carried out. As the study shown, the magnitude and distribution of shear force acted on the inner surface of elbow are affected by many factors the distribution of the biggest tangential stress is in the two sides or the downstream of outer buttress surface and is affected by liquid temperature. The largest heat strain is in the two sides and inner buttress surface of elbow, in which the most severe erosion is found, that is, it is a highly possible failure part. Appropriately reducing flow speed, enlarging pipe diameter, R/D-ratio and enhancing liquid temperature may efficiently minimize erosion fracture stress to the pipeline. The research outcome can be a theoretical foundation for the further study on erosion mechanisms of multiphase mixed transmission pipeline.