[Objective] The production of high-quality tobacco leaves is closely related to soil properties and nitrogen conversion. The use of different types of organic materials as soil amendment in tobacco cultivation to improve quality of its produce varies in effects with the type of organic material used, so it is necessary to explore how to apply rationally organic materials in the light of soil conditions.[Method] In this study, four types of organic materials, i.e. rice straw, rape straw, ryegrass and rapeseed cake, were amended separately at a rate equivalent to 100 mg·kg^-1 nitrogen into the soil samples collected from a field under tobacco-rice rotation, high in organic matter (68.2 g·kg^-1) and a tobacco field low in organic matter (17.2 g·kg^-1). Then the soil samples were incubated and analyzed periodically for mineralization dynamics of inorganic nitrogen (NO₃^-, NH₄⁺), soil enzyme activities and microbial functional diversity.[Result] Results show that mineralization dynamics of soil nitrogen in the tobacco soil were closely related to C/N of the organic material used. In the soil high in organic matter the addition of rice straw, rape straw or ryegrass significantly reduced the net nitrogen mineralization rate, and the concentration of inorganic nitrogen was 3.7~7.8 times, 1.1~1.3 times and 1.0~1.3 times lower than that in the control, respectively, while the addition of rapeseed cake low in C/N significantly increased the net mineralization rate and promoted accumulation of inorganic nitrogen in the soil. However, in the soil low in organic matter, the addition of organic material, regardless of type, significantly increased soil nitrification rate, but the addition of rice straw or rape straw significantly reduced the concentration of inorganic nitrogen in the soil during the early culture period. The addition of rapeseed cake significantly promoted the net mineralization rate in a short period of time (7 d), bringing the concentration of soil ammonium up to 3.3~3.7 times higher than that in the control soil, which indicates that soil ammonium came mainly from mineralization of the organic nitrogen in the organic material applied. Analysis of soil biological properties shows that the application of high C/N organic materials significantly promoted soil microbial functional diversity and soil enzyme activities. However, the soil microbial community varied in structure with the type of organic material applied, and with the type of carbon source utilized.[Conclusion] Therefore, rational application of rice straw in the soil high in organic matter is demonstrated to be an important measure to improve quality of flue-cured tobacco. And it is essential to pay high attention to rational application of high-nitrogen organic manure in upland tobacco fields in the light of soil properties, so as to realize the target of the production of high-quality tobacco leaves in different tobacco cultivation areas.