Abstract: According to soil condition in northern drought mountain in Yongdeng and production actual situation of potato, the results indicated that the most suitable NPK combination was CO （NH2）2 375.0 kg/hm2,CaS20s 112.5 kg/hm2,K2S04 600.0 kg/hm2, which can make the yield reach to 20 730 kg/hm2 and it was increased over 80% than local average yield. Besides, the soil in this region contained rich N and P, but severely short of K. K was the most effect factor on potato＇s yield in this region, therefore we should pay more attention to application content of K and reasonable NPK combination to promote potato＇ s yield.