The Si-doped glow discharge polymer (Si-GDP) films are deposited by glow discharge polymerization technology at different tetramethylsilane (TMS) flows. The chemical structure, the composition and the thermal stabilities of Si-GDP films are analyzed by the Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermal gravimetric analysis. The results show that the Si content increases from 0 to 16.62%, when the flow of TMS changes from 0 to 0.06 cm3/min. The relative content of SiC, SiH, SiO, SiCH3 increases with TMS flow rate increaseing. As TMS flow increases, the thermal stability of Si-GDP film becomes good.