During the welding in the workshop of the motor factory, it will generate some harmful gas. How to make the cost of construction and the running process low, and assure that the harmful things are discharged, take an practical engineering for example, analyzes the inductive ventilation way and research the numeric model, and compare with the normal ventilation way, to draw a conclusion, by the way elevation of 15 degrees through inductive ventilation effect is also very good, furthermore, the running can save energy.