Sand culture was used to investigate the effect of combined application of citrate soluble potassium and potassium sulfate (in ratio of 1﹕3, 1﹕1 and 3﹕1) on root traits, root activity and potassium accumulation of flue-cured tobacco. The results showed that combined application of citrate soluble potassium and potassium sulfate promoted tobacco root growth and development, which was superior than the single application of citrate soluble potassium or potassium sulfate；potassium content in upper, middle and lower parts of flue-cured tobacco were increased by 7.60%, 23.24% and 39.95% with combined application of citrate soluble potassium and potassium sulfate, compared with that of single potassium sulfate application; while total leaf potassium content distribution rate were increased by 8.41%, 20.91% and 42.03% with citrate soluble potassium and potassium sulfate applied in the ratio of 1﹕3, 1﹕1 and 3﹕1, respectively. Thus citrate soluble potassium in the percentage of 75% and potassium sulfate 25% showed the best treatment effect.