This study evaluated and optimized the thermal environment inside an air-conditioned train stationbuilding using the computational fluid dynamics (CFD) method. The impacts of some air-conditioningdesign parameters such as supply air temperature, velocity, altitude and incidence angle on indoorthermal environment were discussed. The primary air-conditioning design scheme was optimized. Thenumerical results showed that when cooling loads in the waiting hall and entrance hall of the trainstation building kept unchanged, alternations made to the cooling air supply scheme in waiting hallwould have little effect on the air distribution in entrance hall. The uniformities of velocity andtemperature distributions in waiting hall showed well when side supply scheme was applied. Changingsupply air temperature, velocity, altitude and incidence angle had great effects on thermal environmentin the train station building. For stratified air-conditioning, in order to obtain satisfactory indoor thermalenvironment the supply air altitude should be at mid-height of the building with zero angle of incidencefrom horizontal. The results also indicated that analyzing the effect of design parameters on indoorthermal environment by CFD method provided an effective way for the optimization of design scheme.