To clarify the alkaline nitrogen (AN) content, spatial distribution, and influencing factors of tobacco-planting paddy soil in Hunan, 2 698 topsoil samples were collected, and AN contents were tested. Meanwhile，the distribution characteristic of AN content and the potential influencing factors including planting system, plough layer thickness, altitude, soil pH, organic matter, and soil particle composition were explored. The results showed that AN content was abundant, with the range of 57.10 – 447.40 mg/kg (mean of 183.78 mg/kg). 46.55% of soil samples were in the suitable range of AN (110 – 180 mg/kg) for tobacco-planting. Average AN content was higher in 10 counties (districts), including Anren, Guiyang and Linwu, while within the suitable range in other 16 counties (districts). AN content was spatially decreased from southeast to northwest. AN content was lower in tobacco-corn rotation, and increased with the increases of plough layer thickness, soil pH and organic matter content. A parabolic relationship was found between AN content and altitude (highest AN content occurred within 150 – 250 m altitude). AN content increased with the proportion of silts and decreased with the proportion of coarse sands. In conclusion, the spatial distribution of AN content is heterogeneous in tobacco-planting paddy soil in Hunan, and significantly affected by planting system, plough layer thickness, altitude, soil pH, organic matter, and soil particle composition. Therefore, rational regional fertilization strategies should be formulated according to local conditions.