Glass through-hole adapter plate is a typical vertical transmission structure widely used in three-dimensional integrated package circuits. Based on the demand of RF signals for the use of small-diameter, narrow-pitch vertical vias, glass vias with a depth-to-width ratio of 8:1 and a minimum diameter of 25.68 μm were obtained based on a photosensitive glass substrate using UV exposure, heat treatment, and wet etching methods. The mechanism of modification of photosensitive glass during the exposure process was obtained by studying the effect of exposure amount on the through-hole preparation process of photosensitive glass through-hole preparation. The experimental results show that with the increase of exposure, the through-hole aperture increases, and the photosensitive glass modification process is a gradual modification process from the front to the back side from the surface to the inside. This provides key process support for the preparation of glass through-hole adapter plates.