Abstract: The effects of application of fertilizer K on the quality of flue-cured tobacco in Sichuan Province were studied.The results show that applying fertilizer K can raise the contents of potassium and reduced sugar，decrease the contents of calcium，magnesium，nicotine and protein in flue-cured tobacco.It is concluded that the effects of the application of fertilizer K on the quality of flue-cured tobacco in three soils are different evidently，the effect is little in red soil and significant in calcareous purple soil and yellow soil.