Abstract: The effects of water extracting on flue-cured tobacco leaves in mature stage were studied. The results showed that potassium content in tobacco leaves decreased after water extracting. The losing rates of potassium ion were from 0.099% (priming of L2 and L4) to 0.2437% (cutters of L1). The stalk positions in the same plant of control and treatment L3 in order of potassium-losing rate were tips > cutters > priming, of L1 treatment were cutters > priming > tips, and of treatment L2 and L4 were cutters > tips > priming.