A reasonable air inlet location not only provides a good ventilation in the building, but also reduces air-conditioning energy consumption at the same time. By adopting the computational fluid dynamics (CFD) method, a simulation test has been carried out of the indoor air environment of industrial buildings under the combined action of thermal ventilation and mechanical ventilation, followed by a tentative inquiry into the influence of different mechanical air supply pressure and position of air supply outlet on the ventilation effect of heat source workshop and air distribution characteristics. Studies have shown that the intensity of the supply pressure is not necessarily proportional to the significance of the ventilation effect. However, the location of the mechanical air inlets has a great influence on the ventilation effect. Under most conditions, the ventilation effect with Hs/H=0.6 is better than that with Hs/H=0.3 and Hs/H=0.9, which research findings help to provide a certain reference for the design of airflow in the buildings and the design of the air inlet location as well.