This experiment was carried out to study the effect of boron application on the physiological response and the outbreak of Granville wilt flue-cured tobacco. NC2326 and Coker 86(flue-cured tobacco) were transplante dand investigated in all field culture plots for this experiment. Elongation of shoots were retarded, and stem heights were shortened in all boron applied plots and the more boron applied, the greater these tendency was. The ratio of root branching and root discoloration, and contraction by Granville wilt were docreased markedly in boron plots. Amount of harvested loaves (yield) was increased greatly in 2 and 4kg plots of borax and boric acid per 10a, and the increasing tendency was greater in NC2326 variety than Coker 86. Phenol compounds content in harvested leaves were higher in boron applied plots than non-applied, and was higher in Coker 86, Granville wilt resistant variety, than NC2326. The more boron applied, the higher nicotine content in the harvested leaves was.