In this paper,KeXinYiHao(one kind of the potato) madeas experiment element,the effect of different amount of K on the yield and quality of potato was stadiod.The results indicated that the application of K could enhance the nourition growth of the potato,improve the organism yield,promote the stalk in the soil bigger,and so on improve the economical quantity and productive rate.But too much application of K let the growth of the potato appear the passive effect.The suitable amount of K fertility could improve the starch contents,otherwise,it makes Vc contents decreased.