Abstract: A new type of oat yogurt was developed with oat milk and reconstituted milk as raw materials and commercial yogurt fermentation strains as starter. Sensory score and acidity were served as indexes, the effects of oat milk and reconstituted milk ratio, amount of fermentation strains, fermentation time, and fermentation temperature on the quality of oat yogurt were studied by single factor experiment. Based on the results of single factor experiment, the optimal fermentation process of oat yogurt was determined by orthogonal test. The basic physical and chemical indexes of oat yogurt including protein, fat, amino acid, acidity, pH were analyzed. The antioxidant activity of oat yogurt was evaluated by ABTS and DPPH methods, and the flavor compounds in oat yogurt were determined by GC-MS. The results showed that the optimal fermentation process of oat yogurt was as follows: Oat milk/reconstituted milk was 2:1, the inoculation amount of fermentation bacteria was 0.2%, the fermentation time was 9 hours, and the fermentation temperature was 34 ℃. The oat yogurt produced by optimal fermentation process presented uniform creamy-white, moderate sour and sweet taste and rich in oat fragrance. Thirty-six aroma components of oat yogurt were detected by GC-MS, including esters, acids and aldehydes. Protein content of oat yogurt was close to commercial yogurt, but the fat content of oat yogurt was only 60% of commercial yogurt. In addition, the antioxidant activity and contents of glycine and arginine of oat yogurt were significantly higher than commercial yogurt (P<0.05). Therefore, oat yogurt has higher nutritional value for public, especially for obesity.