Abstract: Chicks are more sensitive for air contaminates than the adult, even the low level pollution can make adverse effect on them. A positive pressure ventilation system with medium filters was installed in a full size chicky to remove the air contaminates. The results showed that the filter can remove 75% of total suspending particle(TSP), 30% of PM10 and 90% of microbes suspending in the inlet air respectively. Compared with the standard growth index, the weight gain increased from 2.5% to 25.5%, and mortality of chicks raised in filtered air reduced by 1% compared with the past average production level. In addition, it seems that the females benefit more than males from the same filtration system, which will be validated in the future by further experiment.