The invention relates to a fertilizer capable of improve the tobacco soil and promote the growth of roots. The fertilizer comprises the following components by weight percent: 60-90% of humus type organic carrier, 4-10% of rooting powder or root growth promoter, 2-5% of plant growth hormone, 2-5% of potassium sulfate and 2-10% of secondary element/trace element fertilizer. By using the fertilizerof the invention, the soil can be improved, the soil organic matters can be increased, the soil organic and inorganic composites can be improved, the water-stable aggregate structure is easy to form,the supply of soil nutrients can be coordinated, the growth of plant roots can be promoted, the effectiveness of nutrients in soil can be increased, the potassium content of plant tissues can be increased, the organic matters of the tobacco soil can be increased, the effectiveness of nutrients in the tobacco soil can be increased, the growth of tobacco can be promoted, the potassium content of tobacco leaves can be increased, the quality of the flue-cured tobacco leaves can be improved, and the fragrance of tobacco leaves can be increased. By using a defined amount of the fertilizer of the invention, the absorption of the flue-cured tobacco to heavy metals such as arsenic can be reduced, the heavy metal enrichment factor of the flue-cured tobacco can be reduced and the contents of heavy metals such as arsenic in soot and smoke can also be reduced.