Objective To explore the effects of Compound Antler capsule on the NO secretion of macrophages, cell cycle and[Ca2 +]i of mouse T lymphocytes.Methods ICR mice were randomly divided into 4 groups:experimental groups were respectively given Compound Antler capsule 233, 467, 1400 mg/kg via intragastric administration once a day and the control group were given the same volume of water for 30 days.NO concentration of mouse peritoneal macrophages was measured by Griess assay.The cell cycle distribution of activated mouse spleen lymphocytes was measured by flow cytometry.Fluorescent probe Fluo 4-AM was used to mark Ca2 + in lymphocytes, and the changes of its fluorescence intensity were observed with the multiscan spectrum.Results The result showed that NO concentration in experimental groups was higher than that in control group (P<0.01).More activated spleen lymphocytes of 467, 1400 mg/kg dose groups were entried into S and G2/M phase than control group (P<0.05).After activated by ConA for 8 min, the intracellular[Ca2 +]i in mouse spleen lymphocytes of 233, 1400 mg/kg dose group was higher than that of control group, respectively (P<0.05).After activated by LPS for 1, 4, 8 min, the[Ca2 +]iin mouse spleen lymphocytes of 233 mg/kg dose group was higher than that of control group, especially at 1 min(P<0.01).Conclusion Compound Antler capsule can improve NO secretion of macrophages and facilitate the entry of mouse spleen lymphocytes from the G0/G1 into the S phase.It also can increase the [ Ca2 +] i of activated lymphocytes to promote their proliferation.Thus Compound Antler capsule can improve the immune regulating ability.