The effects of three trimethoxysilanes with different functional groups on the rheology, dynamic and mechanical properties of ethylene propylene diene rubber (EPDM)/calcium carbonate (CaCO3) composites were investigated respectively. The results showed that the addition of silane increased the value of MH and MH-ML of the compounds. Geniosil XL 33 silane decreased the shear modulus of the EPDM/CaCO3 compounds, and the bound rubber content increased slightly with the addition of vinyl trimethoxy silane (VTMS) and methylacryloxy-methyltrimethoxysilane (Geniosil XL 33) silane in the compounds. The vulcanizates with the addition of the VTMS and Geniosil XL 33 silane showed a significant increase in tensile strength and abrasion resistance; however, ethyltrimethoxysilane (ETMS) silane weakened the tensile strength and abrasion resistance of the vulcanizates. At low strain, the cross-linking and reaggregation of fillers resulted in a high storage modulus of vulcanizates with silane. When the strain exceeded 10%, the storage modulus of the vulcanizates with the Geniosil XL 33 and VTMS silane was higher. The loss modulus and tan δ of the vulcanized rubber with the Geniosil XL 33 and VTMS silanes were lower compared to the ETMS and 0 silane.