Abstract: In order to study the influence of collision between solid particles in gas-solid two-phase flow on erosion, an erosion prediction method based on the Direct Simulation Monte Carlo (DSMC) method for calculation of particle collision and computational fluid dynamics was proposed. Herein, the Eulerian-Lagrangian method was adopted, the gas was taken as the continuous phase, the Navier-Stokes equations were solved, and the particle translation motion was solved by the Discrete Phase Model (DPM). For calculation of particle collision motion, the DSMC method was used to replace the real particles with a small number of sampled particles, and the collision conditions were judged by the corrected Nanbu method. Additionally, the effect of particle collision on elbow erosion rate and particle distribution in gas-solid two-phase flow was studied. The results show that the model error can be significantly reduced by calculating the particle collision with DSMC method, and the average percentage error of Oka model is reduced from 39.2% to 27.4%. For calculation of particle collision, the non-particle area on the inner arch side of the elbow becomes smaller, and the maximum erosion position moves backward 5° along the outer arch axis. Meanwhile, the flanks of the "V-shaped" erosion trace expand outward. Calculating the particle collision with DSMC method could significantly reduce the model error, and due to the small deviation from the experimental results, the Oka model considering particle collision is the best model for erosion prediction.