To observe the damage to immune system in mice,alcohol of different concentration was administered to 6 groups of male BalB/c mice by gavage in doses of 0,0.67(4%),1.33(8%),3.33(20%),6.08(38%),8.00(50%)g/kg BW once a day respectively for 30 days. The functions of the immune system including the cellular immunity,the humoral immunity,the nonspecific immunity,and the NK cell activity were examined. The results showed that: 1) the alcohol can cause damage to the immune system of the mice,2) all mice of the 8.00 g/kg BW group died within 24 hours after the first gavage;3) in the 6.08g/kg BW group,the mortality within 30 days was 82%,and the ability to sweep carbon particles off the blood was depressed;4) the phagocytosis was depressed in the mice of the 1.33g/kg BW group;5)the NK cell activity was depressed in the mice of the 0.67g/kg BW group;6) no statistically significant change in the seven immune system functions was observed in the 3.33g/kg BW group;7) the concentration of alcohol in a health food must lower than 20% when assessing its effect on immunity experimentally with mice.