To obtain stable and uniform quality of oat Laozao and promote its industrial production， the study was first to combined bacteria isolated from Laozao of Ordos with yeast on the fermentation of oat Laozao， and then optimized the fermentation process of oat Laozao by single factor test and orthogonal test. The results showed that the ratio of yeast to bacteria from pasturing area was 1 ∶ 3， among which the proportion of alcohol-producing yeast and aroma-producing yeast was 3 ∶ 1， and the proportion of 2#， 4#， 5# was 1 ∶ 1 ∶ 1. The best fermentation conditions were determined as follows： the amount of complex bacteria was 10%， fermentation at 30 ℃ for 24 h， and then fermentation at 50 ℃ for 48 h， the sensory evaluation of oat Laozao could be up to 9.1 score. The results could provide technology support for the industrial production of oat Laozao.