Method for increasing content of aroma substances in tobacco leaves

The invention discloses a method for increasing the content of aroma substances in tobacco leaves, which comprises the following steps: 1) sealing water, oil cake and brown sugar in a fermentation container according to the mass ratio of (10-12): (2-3): (1-1.5) for 2 months to obtain oil cake enzyme, and reserving a fermentation space which is 20-30% of the total volume of the container at the upper part of the fermentation container; 2) when the flue-cured tobaccos are transplanted, diluting the withered enzymes by using water which is 1000 times of the volume of the withered enzymes to obtain a first diluent, 10-15 days after transplanting, irrigating the flue-cured tobaccos by using the first diluent as root fixing water, irrigating the roots of the flue-cured tobaccos once every 10-15 days after the first diluent is irrigated, and continuously irrigating the roots for 2-3 times; and (3) after the flue-cured tobacco enters a mature period, diluting the oil cake enzyme with water which is 600-800 times of t