A kind of nonfunctional silsesquioxane (SSQ), methylsilsesquioxane (Me-SSQ), was used to modify cyanate ester resin (CE) in this paper. First, methylsilsesquioxane (Me-SSQ) was synthesized by the hydrolysis and condensation of methyltriethoxysilane. Then a series of Me-SSQ/CE hybrids containing 0wt%, 1wt%, 5wt%, 10wt% and 20wt% of Me-SSQ were prepared. The effect of Me-SSQ content on the curing behavior and thermal properties of materials was investigated by using Fourier transforms infrared (FT-IR) spectroscopy and thermogravimetry (TG), respectively. FT-IR results indicate that the addition of Me-SSQ does not show significant effect on the conversion of CE. However, TG data show that Me-SSQ improved the thermal properties of CE greatly.