New silicone rubber/etheylene propylene diene rubber(SiR/EPDM) blended insulation materials for solid rocket motor were prepared by mechanical blending silicone rubber with EPDM.The insulations were characterized by liner ablation test.Mechanical properties and thermal properties were studied.Ablation test show that with increasing the content of EPDM in SiR/EPDM the linear ablative ratios decreased.When SiR/EPDM is 60/40,the linear ablative ratio decreased to 0.09 mm/s due to forming a relatively tough and rigid inorganic char layers.SiR/EPDM presents higher thermal stability in comparison with EPDM and better mechanical properties in comparison with silicone rubber respectively.