Oat bran protein isolate was prepared from defatted oat bran by isoelectric precipitation of dilute alkali extract. The enzymatic pretreatment of oat bran using Viscozyme L, a kind of multi-component carbohydrase, was introduced into traditional process, and the pretreatment conditions were optimized by response surface analysis(RSA). The optimum parameters of enzymatic pretreatment are as follows: the amount of enzyme 3.02 FBG/g, pH 4.6, incubation temperature 44℃, incubation time 2.8 h. Compared with traditional process, the protein extraction rate is increased from 6.6% to 56.2%. Meanwhile, the purity of protein is increased from 72.9% to 81.7%.