Abstract: The flow fields of air in a large public-room with high ceiling (12 m×15 m×10 m), processed by air handling unit (AHU) and possibly accommodating many people, were mathematically modeled, theoretically analyzed in fluid dynamics and thermodynamics, numerically simulated with CFD software and experimentally evaluated. The influence of the AHU height on the distributions of air velocity vector field and temperature field was investigated. The simulated results show that the AHU height, aligned along vertical symmetric axis, has a major impact.For example, as the height decreases from 8 to 6 m, the velocities and temperatures of the air (0~3 m above ground) increase, with their distributions satisfying well the requirements for heating, ventilation, cooling and energy-saving. The simulated and measured results were in good agreement. We suggest that the simulated results of some technological interest in AHU installation.