The microchannel plate (MCP) is a core device of the image intensifier for the characteristic of the electron gain. The electron rinse is a common way in the flow of the microchannel plate produce but it also changed the other characteristics of the microchannel plate. To study the effect of the electron rinse on the output signal to noise ratio and the electron gain of the microchannel plate, the method of the output signal to noise ratio test and the electron gain test based on their definition are discussed. The microchannel plate parameters test system is designed and the microchannel plate is rinsed by electron in the microchannel plate parameters test system. The output signal to noise ratio and the electron gain of the microchannel plate are tested in the process of the electron rinse at different stages. The causation of the variation of the output signal to noise ratio and the electron gain is analyzed.