Objective To investigate the effect of Jianpi Bushen Yifei Formula on improving airflow limitation of rats with chronic obstructive pulmonary disease（COPD）by detecting COX-2 and p38 MAPK protein in lung tissue,and study its mechanism.Methods 40 Wistar rats were randomly divided into 4 groups（n=10 each）:normal group,model group（COPD rat model established）,COX-2 inhibitor group（COPD model rats receiving celecoxib 10 mgokg-1 od-1）and Jianpi Bushen Yifei Formula group（COPD model rats receiving Jianpi Bushen Yifei Formula 25.2 gokg-1 od-1）.The FEV0.3,FVC,PEF and MMEF in each group were determined.The expression level of COX-2 and p38 MAPK protein in lung tissue were detected by immunohistochemistry.Results Significant decrease of FEV0.3,FEV0.3/FVC,PEF and MMEF were found in model group,COX-2 inhibitor group and Jianpi Bushen Yifei Formula group when compared with normal group（P<0.01）; FEV0.3,FEV0.3/FVC,PEF and MMEF of COX-2 inhibitor group and Jianpi Bushen Yifei Formula group were significantly improved when compared with model group（P<0.01）; MMEF in Jianpi Bushen Yifei Formula group was significantly improved when compared with COX-2 inhibitor group（P<0.05）.The expression of COX-2 and p38 MAPK in model group,COX-2 inhibitor group and Jianpi Bushen Yifei Formula group were significantly increased compared with normal group（P<0.01 or P<0.05）; The expression of COX-2 in COX-2 inhibitor group and Jianpi Bushen Yifei Formula group were significantly decreased compared with model group（P<0.01）; the expression of p38 MAPK in Jianpi Bushen Yifei Formula group were significantly lowered than model group and COX-2 inhibitor group.Conclusion Jianpi Bushen Yifei Formula can improve airflow restriction by inhibiting COX-2 expression in COPD rats,which may be related to down-regulation of p38 MAPK expression.