Two NLO-functionalized epoxy polymers were synthesized and sol-gel technique was introduced into the polymers to achieve the stable second-order nonlinearity. The obtained polymers were characterized with thermal analyses, FT-IR, UV-visible spectroscopy and scanning electron microscopy. The condensation between silanol groups occurred between 100℃ and 200℃ so that the couring and poling were performed at 220℃. The corsslinked and poled polymer films showed high nonlinearity (d₃₃=41 pm/V) and better thermal stability compared to prepolymer, which maintained its nonlinerity up to 100℃ whithout significant loss of NLO activity.