Objective To investigate the role of macrophage in asthma. Method We adopted thirty mice for OVA challenged group,thirty for OVA rechallenged group and ten for the control group to collect the bronchoalveolar lavage fluid and do periotoneal cavity irrigation and observe the quantity change of the cells in different time. Result After challenging,at the second,fifth,seventh day,both absolute number of alveolar macrophage,abdominal cavity macrophage,total BALF cells of challenged and rechallenged group were more than that control group. At the same time,in the challenged group,the reaching peak time and descending tendency of alveolar macrophage showed correlation with abdominal cavity macrophage. Conclusion There is a possibility that the the macrophage may migrate from abdominal cavity to alveolar after being challenged and present foreign antigen.