Abstract: The situation of titanium foil of high power electron accelerator (1.2 MW)extraction window was studied, because the operating temperature of titanium foil should be controlled within 150 ℃, forced aircooling is the only way to disperse the heat (under such temperature, the effects of heat dispersion of heat radiation and conduction can be neglected). With the fluid analog software (Fluent), the relationships among cooling efficiency of titanium foil, initial air velocity and distance, existence of refluent zone and its affects were analysed, also the structure of extraction window was primarily optimized. Additionally, simulation analysis was made on the closed space formed by additional protective window. Non-homogenous-distribution scanning has been proved that the output capacity of