In this paper, the particle flow inside the nozzle is simulated by Computational Fluid Dynamics (CFD) method and the numerical results are verified by experimental observation. The motion trajectories of incident particles in different regions are investigated through trajectory analysis. In addition, the erosion damage mechanism was analyzed by the surface morphology and impact characteristics of the main abrasion region. The results show that the particle impact position gradually moves forward as the particle incident position moves away from the inlet center. Sensitivity analyses showed that erosion rate was most sensitive to pump pressure; impact frequency, impact velocity and impact angle were most sensitive to particle size, pump pressure and particle size, respectively. Due to the low angle impact of particles, the corresponding erosion damage mechanism is micro-cutting. Display omitted •The trajectories of particles incident from varying regions of the inlet are discussed.•The sensitivity of varying parameters to the impact characteristics was evaluated.•The mechanism of particle erosion on the nozzle was comprehensively elucidated.•The work contributes profound insights into the erosion behavior of AWJ nozzles.