Aiming at the cavitation flow and cavitation wear problems in injector nozzle holes of diesel engine, a 3D simulation model of fuel flow inside nozzle hole was established, and the accuracy of model was verified by visual test. Based on Rrs erosion risk prediction model, the microjet velocity, water hammer pressure and erosion intensity coefficient were introduced into the formula to establish a prediction model of cavitation risk in injector nozzle holes. The quantitative characterization of the location of cavitation damage was realized. The model was used to study the effects of different equivalent inlet radius, different inclination angles and different equivalent surface roughness on the cavitation wear of injector nozzle holes. The calculation results show that the cavitation wear area is mainly located at the entrance and upper surface of nozzle hole, and the effect of the equivalent inlet radius on the cavitation wear degree is greater than that of the equivalent surface roughness and the nozzle inclination angle. Therefore, the priority can be given to increasing the corner radius of nozzle inlet to reduce the hole erosion wear and hence improve the life of injector.