Abstract: In order to investigate the effects of calcium and magnesium rates on the root potassium uptake, effluent and leaves potassium accumulation in flue-cured tobacco, solution culture experiment which included normal level，lower calcium level，high calcium level, lower magnesium level，high magnesium level treatments was conducted. The results showed that, high calcium level and magnesium improved the potassium uptake, effectively reduced the effluent of potassium in the root, increased the net uptake of potassium at late growth stage, effectively regulated the circulation of potassium in whole tobacco plant, and increased the potassium content in flue-cured tobacco leaves. The contents of potassium in upper, middle and lower leaves increased by 0.38, 0.41, 0.69 percentage points under high calcium treatment; and increased by 0.31, 0.42, 0.60 percentage points under high magnesium treatment. Under the condition of this study, high calcium and magnesium treatments could increase the root potassium uptake, promote the xylem sap and ploem potassium circulation, reduce the root potassium effluent, enhance the leaves potassium accumulation, increase the potassium content of upper, middle and lower leave.