Abstract: Potato is a typical K-favoring crop and has a great demand on potassium. However, shortages and over-use of potassium are common existing in agricultural production, therefore, it is essential to understand well about the potassium nutritional characteristics of the potato, based on which to conduct the appropriate nutrition management and determine the optimum rate of potassium. The establishment of potassium nutrition diagnosis in field will be beneficial for potassium fertilizer application precisely and timely. In addition, a new diagnostic method was proposed to provide a reference for the field potassium nutrient management of potato.