The effect of four types of silane coupling agents on the mechanical and thermal properties of silicone rubber and ethylene–propylene–diene monomer (M-class) rubber (EPDM) blends is studied, namely, isobutyltriethoxysilane (BUS), acryloxypropyltriethoxysilane (ACS), aminopropyltriethoxysilane (AMS), and vinyltriethoxysilane (VIS). ACS and VIS increase the crosslink density of the blends, which results in higher tensile strength, modulus, and thermal stability, but lower elongation at break compared with the other silanes. However, the blend containing BUS shows highest tanδ in the temperature range of 45°C to 200°C. Thermogravimetric analysis shows two steps of degradation for all the samples, but little difference with the varied silanes.