Fuente: WIPO "tobacco agriculture" The invention discloses a foliage fertilizer capable of effectively increasing the boron content of flue-cured tobaccos and a preparing method and an application method of the foliage fertilizer. Thefoliage fertilizer is mainly prepared from borax, boric acid, monopotassium phosphate, ferrous sulfate, manganese sulfate, fulvic acid, phytohormone, chelating agent, cosolvent, surfactant and water.By means of the foliage fertilizer capable of effectively increasing the boron content of the flue-cured tobaccos and the preparing method and the application method of the foliage fertilizer, flue-cured tobacco leaves can efficiently adsorb boric fertilizer, the absorption efficiency is improved, relevant diseases brought to the flue-cured tobacco leaves due to lack of boron are effectively avoided, and the flexibility of the tobacco leaves is improved. In the meanwhile, the foliage fertilizer contains organic components, inorganic components and microelements, and through organic combinationof the nutrients, the growth and nutritive balance of the flue-cured tobaccos can be promoted; meanwhile, the foliage fertilizer is low in cost, and has an important significance in improving the quality of the tobacco leaves and increasing the economic benefit.