Abstract: The mechanism of accumulation and distribution of potassium in flue-cured tobacco plant during the later period of growth was studied by field experiments. The results showed that the accumulation of potassium in tobacco plant tended to increase after topping, and to decrease during the ripening process. The higher accumulation rates of potassium in tobacco plant could be maintained by applying NAA or keeping its top unremoved, and the highest distribution rates of potassium in leaves was found when applying NAA twice. Potassium content was higher in the matured leaves applied with NAA twice or not topped.