The particle size plays an important role in the mechanical behavior of granular geomaterials. With respect to the crushable granular soils, the particle breakage under different pressures leads to the variation of the particle size distribution of soils. Therefore, it is essential to accurately model the particle fracture process to reproduce the key response of granular soils in the simulation. In this study, two simulated approaches, cluster method and replacement method, were performed to investigate the particle size effect for the crushable granular soils by three-dimensional (3D) discrete element method (DEM). DEM simulations were validated through the available results of diametric and oedometric compression tests with the help of the Weibull statistics. Based on the evaluation at particle and assemble-scale, it is found that both the cluster method and replacement method could simulate the particle strength and size dependence of sample failure with a good agreement with experimental results. The particle breakage phenomenon is also successfully modeled in DEM simulation and analyzed by the breakage index. Meanwhile, the computational efficiency was analyzed compared with two simulated methods. The findings in this study can provide a viable approach to investigate the particle breakage effect of the crushable geomaterials.