Objective To investigate the impact of thymalfasin on cellular immune function and lung function of patients with chronic obstructive pulmonary disease(COPD).Methods 216 patients with COPD in our hospital from March 2011 to August 2014 were randomly selected.According to the digital table,they were divided into the study group (108 cases) and control group (108 cases).The control group was given conventional treatment,while the study group was given thymalfasin on the basis of conventional treatment.Then,the cellular immune function,lung function of each index of the two groups were statistically analyzed.Results The CD3+,CD4+,CD4+/CD8+ of the study group were significantly higher (all P ＜ 0.05),the CD8+ was significantly lower(P ＜ 0.05),the FEV1,FEV1/FVC were significantly higher than the control group (P ＜ 0.05).Conclusion Thymalfasin can effectively improve the cellular immune function and lung function of patients with COPD.