The ANSYS parametric design language was used to established the mesoscale representative volume element(RVE) model to estimate effective elastic properties including elastic modulus and Poisson′s ratio of explosive B. Results show that the calculated results agree with that from the literature. The influence of particle size distribution on effective elastic properties was also studied, and it can be inferred that the model can predict the effective elastic properties without the particle distribution, and the error between the calculation results and the experimental results is less than 10%.