to obtain a high spatial resolution of a image intensifier based on microchannel plate (mcp), the long tail in the exit energy distribution of the output electrons (edoe) is undesirable. the existing solution is increasing the penetration depth of the mcp output electrode, which will result in a serious gain reduction. coating the mcp output electrode with efficient secondary electron yield (sex) materials is supposed to be an effective approach to suppress the unfavorable tail component in the edoe without negative effects on the gain. in our work, a three-dimensional mcp single channel model is developed in cst studio sltite to systematically investigate the dependences of the edoe and the gain on the sey property of the coated material, bawd on the finite integral technique and monte carlo method. the results show that besides the high sey of the coated material, the low incident energy corresponding to the peak sey is another essential element affecting the electron yield in the final stage of multiplication and suppressing the output energy spread.