We have successfully utilized the sol-gel method to synthesize epoxy-silica hybrid material at nanoscale. Using the sot-gel process we could overcome many disadvantages of conventional composite materials. In this research, two different methods are recommended a one-step process and a two-step process - to synthesize epoxy-silica hybrid materials. The coupling agent, gamma-glycidoxypropyl-methyldiethoxysilane (KBE-402), was utilized to modify the surface properties of the silica via the sol-gel process. The role of the coupling agent is to provide covalent bonding between the epoxy resin and silica. This method could reinforce the interfacial force of the hybrid material and promote the thermal properties of the materials. The thermal properties of the epoxy-silica materials were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). From these results, we noted that the best reaction time in the one-step process is 2 days and the addition of the inorganic component enhanced the thermal stability of the hybrid materials. On the other hand, the two-step process led to a phase separation phenomenon after mixing epoxy resin and precursor without coupling agent. The coupling agent could avoid the phase separation problem of hybrid materials and enhance the thermal stability of the materials through this process. At the same time, the T-g of the materials increased proportionally to the content of silica from 80 degrees C to 113 degrees C.