Oat protein isolate was extracted by alkali extraction acid precipitation with naked oat as raw material. The protein extraction rate was 75% under the condition of the ratio of material to liquid 1∶10 g/mL, pH = 8.5(alkali extraction),pH=4.5 (acid precipitation) and T = 20 ℃. The functions, such as the emulsibility, foamability, moisture retention and viscosity of oat protein isolate, were measured under the condition of different pH, ionic strength and concentration. The results showed that the emulsibility, foamability and moisture retention were the lowest near the isoelectric point; the influence of ionic strength on each functional index was different; there was a positive correlation between protein concentration and its viscosity.