The Al2O3 particles reinforced TDE-85 resin-based composite materials was prepared;surface modification technique was applied to the Al2O3 particles by using silicon hydride coupling agent (SCA). The effect of surface modification on mechanical properties was studied. The solid reaction temperature of composite materials was measured and the activation energy was calculated, the tensile fracture surface was observed with a scanning electron microscope. The experimental results show that when the content of Al2 O3 particles is 2wt%, the reaction speed is faster. Moreover, when the content of silicon hydride coupling agent arrives at 4wt%, the surface modification of Al2O3 particles is the best, and the comprehensive mechanical properties of composite can be improved.