Abstract: The anti-oxidative indexes in the serum and whey of the cow suffered from alcohol positive milk(APM) were detected. And the mechanism of APM was probed from the free radicals/ disorder in this test. Meanwhile, concentrations of microelement Zn,Cu,Mn,Fe in the serum and milk were detected and the relationship between concentrations of microelement and the free radicals/ metabolism was investigated. According to the result of experiment，excessive anti-oxidative reaction occurs and the total anti-oxidation capability goes down in the cow with APM. The system of anti-oxidation in the body can not eliminate the active oxygen and metabolites effectively，maybe the epithelial cells of mammary gland were mini-injured by the surplus of free radicals. It leads to the occurrence of alcohol positive milk.