【Objective】Nitrogen (N) and Phosphorus (P) are two essential mineral nutrients for plant growth, and important parts of organic nutrient and soil fertility. As two restrictive elements in the terrestrial ecosystem, they play important roles in growth and development of plants, community composition of the vegetation and structure and function of the ecosystem as well. As ecosystems vary in soil microbial activity, they do in recycling and transformation of soil N and P and in decomposition and accumulation rate of organic matter, thus leading to significant variation of the ecological stoichiometry of soil N/P. Therefore, the study on spatial variability of the ecological stoichiometry of soil N/P and its influencing factors in the terrestrial ecosystem at a provincial scale is the fundamental basis of the study on changes in trophic structure, population succession and chemical elements recycling in the terrestrial ecosystem.【Method】 Based on the data of the 16 582 soil samples collected in the topsoil layer (0~20 cm) of the farmlands during implementation of the project of soil-test-based formulated fertilization in Jiangxi Province in 2012, values were assigned to the qualitative factors, i.e. parent material, soil type, farmland-use type, straw incorporation pattern and nitrogen fertilization (divided into 4 levels), and one-way variance analysis, ordinary kriging analysis and regression analysis were done of the data to quantify the ability of each factor to explain spatial variability of the ecological stoichiometry of soil N/P ratio independently.【Result】Results show as follows: ① The soil N/P ratio in the topsoil layer ranged from 0.28 to 13.63, with an average of 3.38, which indicates that the soil N/P in the cultivated land ecosystem of Jiangxi Province is at the level of medium on the lower side, and that the biological nitrogen fixation rate in the cultivated land ecosystem is at a quite high level. The coefficient of variation was 45.56%, indicating that soil N/P is moderate in variability. The nuggest/sill ratio was 60.54%, indicating that soil N and P is weak in spatial dependence, varying between structural factor and stochastic factor, and the latter played a more important role in spatial variability of soil N/P ratio. ② Soil N/P ratio was significantly related to elevation (p<0.01, r=-0.038), TN (p<0.01, r=0.681) and TP (p<0.01, r=-0.665), suggesting that elevation is a major factor affecting spatial distribution of soil N/P and that soil N/P depends mainly on TN and TP contents. ③ The spatial distribution of soil N/P ratio appeared to be quite smooth relatively, with high values over in Wuyuan of Shangrao, Jinxian of Nanchang, Xiangdong and Lianhua of Pingxiang, Fenyi of Xinyu, Lichuan of Fuzhou and Dingnan of Ganzhou. ④ The five factors, parent material, soil type, farmland-use type, straw incorporation pattern and nitrogen fertilization rate, all had significant impacts on spatial variability of soil N/P ratio (p<0.01), but varied in degree. Parent material explained 2.4% of the variability; type, sub-type and genus of the soil did 1.8%, 2.2% and 3.0%, respectively; farmland-use type did 2.2%; straw incorporation pattern did 13.0%; and N fertilization rate did 27.2%. 【Conclusion】The factor of N fertilization rate is far more capable of explaining independently spatial variability of the soil N/P ratio than the other factors, indicating that it is the main factor determining soil N/P ratio in the topsoil layer of Jiangxi Province. Therefore, in order to improve the ability of the farmland ecosystem to fix nitrogen biologically and sequestrate nitrogen, here are two suggestions. One is to devote more efforts to improving farmers’ knowledge about the use of chemical fertilizers, especially Nitrogen fertilizer, through propaganda and related technical training, vigorously extrapolating the soil-test-based formulated fertilization technology and stimulating farmers to rationalize fertilizer usage. And the other is to raise subsidies and implement preferential policies for use of organic manure and accelerate development of the green manure industry coupled with the extension of straw incorporation.