The flow plate makes bad gases in different height discharged from different parts. The ventilation cabinet discharges internal air out at the speed of 0.5m/s to guarantee there is not any residual air inside, so the ventilation efficiency is high and ventilation capacity is 450-1600m3/h. The glass window may be dragged up and down. It can be stayed on any position to provide safer, more comfort test space for experimenter.