Objective: This paper investigates Shenmai Injection’s effect on the cellular immunity of patients with acute exacerbated chronic obstructive pulmonary disease (AECOPD). Methods: 92 cases of AECOPD patients are randomly divided into two groups----control group and treatment group, each with 46 patients. Patients in the two groups are given the same treatment such as anti-inflammatory, astiasthmatic, eliminating phlegm, inhale oxygen. Based on conventional treatment, the treatment group dissolves 40mL of Shenmai Injection in 250mL of injection glucose (5%). Such solution is dripped in vein continuously for two courses of treatment, with ten drops for a course of treatment and once a drop. Indexes of CD+3, CD+4, CD+8of peripheral blood T lymphocyte subsets and ratio of CD+4/CD+8 are tested before two weeks and after two weeks of the treatment, in order to discuss the effect of Shenmai Injection on the cellular immunity of patients with acute exacerbation of chronic obstructive pulmonary disease. Results: After two weeks' treatment, the indexes of CD+3, CD+4 raise up, the indexes of CD+8 go down, and the ratio of CD4+/CD8+ increases. In contrast, there is a significant difference for the patients before the treatment; So is the same with Indexes of CD+3, CD4+, CD8+ and ratio of CD+4/CD+8 to the patients in the treatment group and those in the control group after two weeks. Conclusion: Shenmai Injection can improve the AECOPD patient’s cellular immunity.