The dynamic EROSION characteristics of pipe bends exposed to gas-solid two-phase flow are investigated by using an EROSION-coupled dynamic meshing method to elucidate the EROSION failure phenomenon that is common in pipe elbows, transporting coal fly ash and subjected to particle EROSION. The static mesh is compared with the EROSION-coupled dynamic mesh method by CFD. The dynamic EROSION characteristics of bends with different r/D ratios, D and r are investigated before and after surface deformation under gas-solid two-phase flow. The results lead to the following conclusions: Improved performance of the EROSION-coupled dynamic mesh by taking full consideration of the coupling between the EROSION-induced surface deformation and the particle motion under prolonged EROSION. The EROSION rate at the elbow changes significantly upon surface deformation, and the sites with a high risk of EROSION shift downstream. With increasing of deformation, the larger the r/D ratio, the more obvious the concentration of EROSION location evolving downstream. As D decreases, the high-risk EROSION areas become more concentrated. In particular, the emergence of the “bending increase” phenomenon leads to a different perception of how r/D ratio and the diameter affect EROSION in static-grid simulations: a larger r/D ratio of the elbow makes it more sensitive to surface deformation and increases the EROSION rate. This study leads us to consider the coupled deformation of EROSION in the context of EROSION problems, which has important implications for predicting the service life of overflow components.