Using the properties of silane coupling agent (SCA) to be reactive or compatible with organic matter, the experimental method of SCA to improve the interfacial adhesion between SiO2 coating and polyimide (PI, Kapton) matrix was discussed. This method improves the bonding strength between the SiO2 coating and PI matrix, while weakening the internal stress caused by temperature changes. Under hydrothermal conditions, the PI surface was removed with low concentration NaOH. Three different SCAs, such as γ-aminopropyl triethoxysilane (KH-550), γ-glycidoxypropyl trimethoxysilane (KH-560) and γ-methacryloxypropyl trimethoxysilane (KH-570), were selected to interact with PI surface in a solvothermal environment. The combination of SCA and PI was evaluated by water vapor and irradiation test. The surface morphologies of samples were characterized by SEM and material analysis microscope. The surface wettability was measured by contact angle meter, and the light transmittance was characterized by UV-vis spectrophotometer. After 0.1 mol/L NaOH hydrothermal treatment, the water contact angle of Kapton surface decreased from 77° to 53°. KH-550 could form a uniform hydrolyzed layer on the Kapton surface under solvothermal environment. After the water vapor and irradiation test, the hydrolyzed layer remained intact and the light transmittance did not decrease. However, the hydrolyzed layers of KH-560 and KH-570 fell off, and the light transmittance decreased by 4.4% and 9.3%, respectively. Although SCA can effectively improve the wettability of polymer matrix and the interface interfacial adhesion between inorganic coating and matrix, in the selection of SCA, whether it can react with polymer surface must be considered. If the SCA is not firmly bonded to the polymer matrix, it is more likely to cause the coating to crack and fall off, becoming a potential instability factor.