A pot experiment was conducted to study the effects of soil potassium supply level on the growth, indices of physiology and biochemistry, and the potassium content in lower leaves of tobacco plant. The results showed that in early budding stage, when the potassium content of lower leaves was below 0.9%, the tobacco plant was deficient in potassium, when the content ranged 0.9%-1.25%, the tobacco plant was less deficient in potassium, and 1.26%-1.6% was potencially deficient, over 1.60% was sufficient. The content of soil available potassium was lower when below 55 mg/kg, deficient when 55-110 mg/kg, moderate when 110-160 mg/kg, relatively rich when 160-230 mg/kg, and rich when over 230 mg/kg.