To investigate the clinical efficacy and mechanism of the combination of montelukast and Chaipu Huoxue Zhike Decoction,and to evaluate the effect of the combination therapy on the cellular immune function of patients with cough after lung infection and Shaoyang cardinal disadvantage and phlegm drinking stasis syndrome.Methods:A total of 90 patients with cough with the syndromes of dysfunction of Shaoyang pivot,phlegm and fluid retention,and blood stasis after a lung infection admitted to the Infection Department of Wangjing Hospital from February 2019 to February 2020 were selected as the research objects and and were divided into a control group(n＝45,given Monelukast)and an observation group(n＝45,given Montelukast and Chaipu Decoction)by using a randomized numerical table.The treatment effect,cough improvement,cellular immune function,and pulmonary function in the two groups were compared.Results:The total effective rate of the observation group was higher than that of the control group(95.56% vs 80.00%),and the comparison was significant(P<0.05).After 14 d of treatment,CD4+ and CD4+/CD8+ increased in both groups,and CD8+ decreased significantly compared with the pre-treatment level.After 14 d of treatment,FVC,FEV1 and FEV1/FVC in both groups increased significantly compared with those before treatment,and the comparison between the two groups was significant(P<0.05).Conclusion:Using Montelukast and Chaipu Huoxue Zhike Decoction for the treatment of patients with cough after lung infection can improve cellular immunity and lung function,which is worthy of be promoted.