Abstract: To investigate effects of Chlorgenic Acid (CHA) on proliferations and secretion function of mouse spleen lymphocytes in vitro. Mouse spleen cells were prepared by aseptic separation and in vitro cultured in RPMI 1640 containing 10% fetal blood serum. The stimulant Concanavalin (ConA) and Lipopolysaccharide (LPS) were added in culture medium with different CHA concentrations of 40, 80, 160 μg/mL. After cells were cultured for different time, MTT assay the proliferations of T and B lymphocytes, ELISA and Griess methods were used to detected TNF-α and NO levels. The results showed that proliferation and survival rate of ConA-induced T lymphocytes and LPS-induced B lymphocytes treated with low and medium CHA concentration were improved, and cellular transformation significantly inhibited at high concentration of CHA. CHA could enhance the NO secretion of T and B lymphocytes treated with CHA; TNF-α secretion of T lymphocytes basically did not be affected. TNF-α secreted from spleen B lymphocytes was promoted at medium concentration of CHA, but inhibited at high CHA concentration. CHA promoted the proliferation of spleen T and B lymphocytes from mice treated with cyclophosphamide, but there was not a significantly effect of CHA on NO secretion. The results suggested that CHA might affect lymphocyte proliferation and cytokine secretion to perform immunomodulatory effects.