Abstract: ObjectiveTo study the collagen's development and diversification by using Yi Qi Hou Xue(YQHX)pre-scription of Chinese medicine in pulmonary fibrosis rats at different time and diverse org ans.MethodsEighty male SPF-rate Wistar rats were randomly divided into 4 groups,20 in each group,i.e.the normal control group,the model group,the YQHX group and the hydrocortisone group.Pulmonary fibrosis rat model was formed by bleomycin injection via trachea.The ratio of Ⅲ and Ⅰ collagen at different time and diverse organs was observed by two distinct dy ing methods of picrosirus red and Harris-Einfred.ResultsOn the 28^th day after YQHX treatment,the levels of Ⅲ and ⅳ collagen was decresed,and the ratio showed statistically significant difference compared to model group(P<0.05).And it showed no statistically significant difference on the 7^th day after the treatment.ConclusionThe YQHX prescription could inhibit the process of airsacculitis and prevent pulmonary fibrosis to some extent.