Elastic moduli are important parameters for characterizing granular materials; however, they are difficult to be characterized theoretically. In this study, contact probability and contact force ratio were used to derive the analytical model of elastic moduli for binary mixture of granular materials. Then the discrete element method (DEM) was used to create the numerical model of binary mixture and obtain the particle contact information. Based on DEM, the analytical expressions for contact probability and contact force ratio of binary mixture were established. The calculation results show that the contact probability and the contact force ratio are affected by the particle size ratio and the content of different particles. When the content of coarse particles exceeds 60%–70%, the stress of the sample is mainly borne by the coarse particles and is almost not affected by the particle size ratio.