Abstract: Using Baiyan 7 and Mongolian Ambassador Yan No. 1 as the test material, the experiment was conducted to understand the effect of potassium doses on grain yield and quality of different oat eultivars in a split-plot design with two factors. It was found that the grain yield first increased and then decreased with the increase of the amount of potassium doses. And the size of potassium doses differentiated the quality of oats. Fertilization of oats with potassium in the dose of 90-135 kg/hm2 reached the maximum of grain yield and the protein content,β-glucan content and oil content of grain in the above mentioned oats,as well as plant height,grain number,main spike length, number of spikelets,grain weight per plant and grain weight,which is the rational fertilization measures to have practical significance to guide the production of oats.