During silanes surface treatment, the hydrolysis degree is important operating parameters for the effective utilization of silanes and dilution multiple of concentrated solution in the building of silane bath. The water soluble mixtures of bis[ trimethoxysilylpropyl] amine ( BAS) and vinyltriacetoxysilane ( VTAS) were choose as raw materials. The influences of dilution and the ratio of BAS on the hydrolysis degree of BAS were studied by spectrophotometer method. The results show that the dilution and increasing of the ratio of BAS are both beneficial to the further hydrolysis of BAS.