<p>This paper proposes a theoretical model for predicting the particle size evolution of crushable granular materials under one-dimensional compression. A statistical distribution model is employed to calculate the contact forces on individual particles within crushable granular assemblies, and the breakage probability of particles in different size classes is derived using the Weibull distribution model of particle crushing strength. Additionally, a fractal model is adopted to characterize the mass-size distribution of fragmented particles. The proposed theoretical model is further validated against experimental data reported in the literature and is shown to effectively capture the particle size evolution of crushable granular materials during one-dimensional compression.</p>