The effects of potassium fertilizer on cotton yield and its changing trends,and the technology of potassium fertilizer application in main cotton production areas in China over the past 50 years were reviewed.The effects of potassium on cotton nutrient,resistance and quality were elaborated.The effects of potassium fertilizer were different in different periods and regions.In recent years,as the promotion of potassium fertilizer and the increase of applied amount,the effects of potassium on cotton yield increase was reduced gradually in some cotton production regions.The necessity of potassium fertilizer,the time and amount of potassium fertilizer application should consider the potassium condition in local soil and the needing rule of fertilization.