Abstract: A series of organic/ inorganic hybrids involving epoxy resin and t riethoxysilane-terminated polycaprolactone elastomer ( PCL-TESi) were prepared via polymerization of diglycidyl ether of bisphenol A (DGEBA) withamine curing agent KB-2 and sol-gel process of PCL-TESi. The organic/ inorganic hybrids were characterized byFT-IR , transmission elect ron microscopy ( TEM) , thermogravimetry analysis ( TGA) and swelling in toluene. Theresult s show that the swelling property in toluene , morphologies and thermal degradation of the hybrids are quitedependent on the content of PCL-TESi. The crosslink network density decreases with increasing of the PCL-TESi.And in TEM , the phase separation morphology of these hybrids is found , which resulted f rom the coagulation ofSi —O —Si networks and the curing reaction of the epoxy resin system. Meanwhile , the size of each phase is in nanoscale. And in TG analysis , the characteristic decomposition temperature at 5 % weight loss is evidently increasedf rom 120. 5 ℃of pure cured epoxy to 277. 6 ℃of 3. 84 % SiO₂ modified epoxy ; this is due to the existence of Si —O —Si when PCL2TESi is added in the hybrid.