Abstract: OBJECTIVE To investigate if ginseng has the effect on enhancing the immunity after micronizing. METHODS The experiment was divided into two parts, part one:96 Balb/c mice were randomly divided into two immunized groups (immune groupⅠand immune groupⅡ). According to body weight, each immunized group was randomly divided into 4 groups:blank group, three dose groups of superfine powder of ginseng (SPG) (166.7, 333.3, 500.0 mg·kg^-1). After gavaged for 32 d, immune groupⅠ:organ index (spleen and thymus), SI (Con A), NK cell activities were measured by splenic lymphocyte proliferation ability and NK cell activities test. Immune groupⅡ:the degree of plantar swelling in mice before and after SRBC stimulation and the anti-volume level in serum was measured by DTH and serum hemolysin experiment. Part two:according to body weight, 60 ICR mice was randomly divided into 5 groups:blank group, model group, three dose groups of SPG (166.7, 333.3, 500.0 mg·kg^-1), each group were administrated for 13 d. Start from the 5th day of the experiment, each group was injected CTX 40 mg·kg^-1 intraperitoneally for 3 d expect blank group to establish immunocompromised model. The number of WBC, organ (spleen and thymus) index, the levels of IL-2, IL-4, IgG and IgM in serum and the activities of LDH and ACP in spleen homogenate were measured. RESULTS Part one:spleen and thymus index in each groups of SPG and the NK cell activities of SPG 333.3, 500.0 mg·kg^-1 group was significantly increased. The antibody volume and the degree of plantar swelling before and after SRBC stimulation in SPG 333.3, 500.0 mg·kg^-1 group were higher than the blank group. Part two:The number of WBC, the levels of IL-2, IL-4, IgG and IgM in serum and the activities of LDH, ACP in spleen homogenate were significantly increased in SPG 333.3, 500.0 mg·kg^-1 group. CONCLUSION A certain dose of SPG has the effect on enhancing immunity in normal and immunocompromised mice, suggesting that ginseng still has the effect on enhancing the immunity after micronizing, which provides the experimental basis for the further development and utilization of SPG.