OBJECTIVE：To optimi ze the optimal composition proportion of 4 ingredients （Panax ginseng ，Astragalus membranaceus，Polygonatum sibiricum ，Lycium chinensis ）in Compound ginseng immune-enhancing formula （CGIF），and to study immune activity and acute toxicity of the extracts with the optimal ratio. METHODS ：The cell activity test was used to screen the crude drug concentration range of 4 ingredients. After treated with different crude drug concentrations of each medicinal material，using the contents of NO ，IL-6 and TNF-α as indexes，uniform design was used to determine the optimal ratio of each ingredient in CGIF. Totally 240 mice were taken and randomly divided into 4 batches，with 60 mice in each batch. Each batch of mice was randomly divided into blank group （normal saline ），model group （normal saline ），positive drug group [levamisole ，4 mg/（kg·d）]，and optimal proportion extract of CGIF low-dose ，medium-dose and high-dose groups [ 0.952 8，1.905 6，3.811 2 g/（kg·d）]，with 10 mice in each group ；they were given medicine intragastrically ，qd，for consecutive 30 d. Except for blank group，mice in the other groups were intraperitoneally injected with cyclophosphamide [ 40 mg/（kg·d）] on the 24th day after first administration，qd，for consecutive 3 d to induce immunocompromised model. The immune activity of the optimal proportion extract was evaluated by determining visceral coefficients ，spleen lymphocyte transformation capacity ，serum contents of hemolysin，IL-2，IgM，IgG and IgA ，phagocytosis function of peritoneal macrophages. Another 20 mice were collected and given the optimal proportion extract 20 mL/kg intragastrically ，twice；acute toxicity of the formula was investigated with oral maximum tolerated dose （MTD）. RESULTS ：The optimal ratio of CGIF was that crude drug mass ratio of P. ginseng ， membranaceus，P. sibiricum ，L. chinensis was 1 ∶ 2 ∶ 2 ∶ 4. The immunological activity experiment showed that theoptimal proportion extract can significantly improve visceral indexes of mice ， spleen lymphocyte proliferation ability serum contents of hemolysin ，IL-2，IgM，IgG and IgA as well as macrophage phagocy tosis ability （P＜0.05 or P＜ 0.01）. The acute toxicity test indicated that oral MTD was over 15 g/kg，which was non-toxic. CONCLUSIONS ：The optimal proportion extract of CGIF can significantly enhance the immune function of mice and are non-toxic.