<p>The injector plays a critical role in energy conversion in Pelton turbines, but intense sediment erosion can lead to local deformation and endanger turbine stability. This study uses a volume of fluid-Lagrange (VOF-Lagrange) multiphase flow model to simulate injector erosion, analyzing the impact of particle parameters and needle opening on wall abrasion morphology and predicting erosion loss. Results show that particle diameter has the greatest influence on sediment discharge and component erosion, followed by sediment concentration and needle opening. Vortex positions and particle diameter significantly affect wall erosion distribution. Erosion is most severe at the nozzle contraction, inner rib trailing edges, and needle tip, with the needle’s relative erosion ratio sensitive to particle diameter, concentration, and opening changes. Larger particles increase slip velocity and wall residence time, shifting erosion from banding to sheet and intensifying asymmetry. This study offers insights into injector erosion, providing a foundation for injector optimization in Pelton turbines.</p>