Abstract: The effect of potassium nutrition on some physiological characteristics and yield formation of sweet potato with field culture were studied.The result showed,the application of adequate potassium increased the ATP content of functional leaf and storage root,and the ABA content of storage root in sweet potato.Adequate K application also improved soluble carbohydrate loading in leaf and soluble carbohydrate unloading in storage root,accelerated the transportation of carbohydrate from leaf to storage root,increased the starch content in storage root and the ratio of storage root dry weight to total dry weight,promoted the storage root growth rate.All of those contributed to increase storage root yield.