Polyphenylsilsesquioxane terminated with methyl and vinyl groups, a novel organic-inorganic hybrid low-melting glass (PhLMG), was synthesized via hydrolysis-condensation of phenyltriethoxysilane and termination of silanol groups with hexamethyldisiloxane (MM) and divinyltetramethyldisiloxane ((MMVi)-M-Vi). Fourier transform infrared spectrometry (FT-IR) and H-1 nuclear magnetic resonance spectrometry (H-1 NMR) confirmed the chemical structure of PhLMG, and with the terminating agents increasing, the residual silanol groups accordingly reduced and even disappeared. XRD and FT-IR results demonstrated that PhLMG possessed amorphous ladder-like structure. The mean molecular weight and thermal stability of PhLMG were largely determined by the amount of the terminating agents. The glass transition temperature (T-g) of PhLMG without the terminating agents was 125 degrees C, while T-g of PhLMG markedly decreased after adding the terminating agents. Furthermore, the structural regularity of PhLMG was lowered with the addition of terminating agents. When the molar ratio of the composite of MM and (MMVi)-M-Vi to phenyltriethoxysilane was 0.05, the mean molecular weight and thermal stability maintained at higher level and silanol groups disappeared completely.