The data of hydrolysis degree is an important operation parameter for the cycling utilization of silanes and dilution of concentrated solution in the building of silane bath. In this paper, bis-[trimethoxysilylpropyl] amine (BAS) and vinyltriacetoxysilane (VTAS) were used as raw materials, isopropyl alcohol was adopted as internal standard, and gas chromatography was used to determine the hydrolysis degree BAS and VTAS by measuring the concentration of their hydrolysates, CH₃OH and CH₃COOH, respectively. The effectiveness of the gas chromatography was confirmed further by infrared spectrum, polarization curves and CuSO₄ drop test. The results indicate that gas chromatography can character effectively and rapidly the hydrolysis degree of silanes in BAS/VTAS system, and the results can offer quantitative basis for the evaluation of the property of silane.