Abstract: Microchannel Plate (MCP) with ion barrier films (IBFs) is one of the key components in Low Light Level (LLL) Image Intensifier (I2) tubes in Generation III. Vacuum high-temperature baking process plays a destructive role in the particle blocking and transmitting performance of ion barrier film. Al2O3 thin film density as a function of the temperature of the environment was studied using molecular dynamics simulation. Electron transmittance and ion barrier blocking ratio of Al2O3 thin film versus the energy of incident particles were simulated and calculated using the Monte Carlo method. The dead voltage of Al2O3 thin films was about 235 V, and with the decrease of the incident ion energy, ion blocking ratio increased. When the incident energy was 250 eV, the preventing ability of Al2O3 films on C, N, O ions was 96%-99%. Based on the above factors analysis, with the increase of the external temperature, electron transmittance increased linearly, while the blocking ratio of ion barrier decreased nonlinearly. Optimization and adjustment of high temperature baking time and quantity will contribute to the ion barrier film performance improvement.