Abstract: According to the problems of the higher nicotine contents in tobacco leaves especially top leaves and reducing usability of tobacco leaves in recent years.by analysis of the Influential Factors of breed,climate, soil, elevation as well as other agronomic treatments including mineral elements of N, P, K, transplanting time, plant population, topping, plant growth regulator,the authors put forward the technical measures of reducing nicotine and enhancing the usability of tobacco leaves: ①cultivating breeds with proper nicotine contents; ②shifting the tobacco cultivation toward proper area; ③applying the right amount of N, P, K, balancing applying microelement; ④Rational ascertaining transplanting time , topping density and leaves remainedt; ⑤adopting the plant growth regulator; ⑥reduction of nicotine by supercritical CO2 extraction; ⑦microbial degradation of nicotine etc.