Abstract: Reconstituted milk as raw material treated with different concentrations of sodium selenite was fermented by Saccharomyces cerevisiae and Lactobacillus casei. In order to explore the interaction in the process of fermentation,the pH,probiotic count,oxidation resistance and selenium conversion were tested. The experimental results showed that the increasing concentration of sodium selenite had not significant inhibition of pH values,and showed adverse effect of the number of Lactobacillus casei. And the antioxidant capacity of fermented samples rose up with elevated concentrations of sodium selenite. Within 24 h during fermentation,the sodium selenite conversion rates grew up gradually,of which 2 mg/kg group reached 98% at 24 h and grew faster than other groups. At the same time,2 mg/kg concentration could promote the proliferation of Saccharomyces cerevisiae. After comprehensive evaluation,adding 2 mg/kg sodium selenite in the mixture was better.