In this study, the effect of lye corrosion time on the gain of a microchannel plate is investigated. By adjusting the lye-etching time, the concentration of alkali metals and the roughness of the channel inner wall are visualized via X-ray photoelectron spectroscopy and atomic force microscopy. Results show that reducing the lye-etching time can reduce the loss of alkali metal elements in the inner wall of the microchannel plate without affecting its roughness, thereby improving the secondary electron emission capacity and the microchannel plate gain. Further tests show that higher alkali metals can improve the gain of both the microchannel plates and image intensifier tubes, whereas the noise coefficient in the image intensifier tube does not increase with reduced lye-etching time.