In order to investigate the role of acupuncture in the regulation of cellular immune function, the changes of T lymphocytes subsets (CD₃ ⁺, CD₄ ⁺, CD₈ ⁺), soluble interleukin-2 receptor (SIL-2R) and betaendorphine (β-EP) in the peripheral blood of patients with malignant tumors before and after acupuncture were observed with the double blind method. Forty patients were divided randomly into two groups, 20 for each. One group was treated with acupuncture and the other one used for control. Results showed that acupuncture has the effect of enhancing the cellular immunity of patients with malignant tumors. Acupuncture treatment could increase the percentage of T lymphocyte subsets CD₃ ⁺, CD₄ ⁺and the ratio CD₄ ⁺/CD₈ ⁺(P<0. 01), increase the level of β-EP, as well as decrease the level of SIL-2R (P<0.01). The correlation analysis of three criteria showed there was a positive correlation between β-EP and T lymphocyte subsets and a negative correlation between β-EP and SIL-2R; there was also a negative correlation between T lymphocyte subsets and SIL-2R. Based on these results, a discussion on the acupuncture immunomodulation network was conducted in this article in order to explore the possible mechanism of acupuncture on immunomodulation.