Based on the soil data of 16 823 plow layer (0—20 cm) samples of cultivated land soil collected in Jiangxi Province, the spatial variation characteristics of soil nitrogen and the affecting factors at a province scale were studied by field survey, mathematical statistics analysis and geostatistics analysis methods. The results showed that the average contents of soil total nitrogen (TN) and available nitrogen (AN) were 1.57 g/kg and 164.13 mg/kg, respectively, which indicated that both the TN and AN in the study area were at a rich level. According to semi-variance function analysis, the values of the nugget to sill ratio were 62.03% and 78.97%, respectively, which suggested that the spatial variation of TN and AN in Jiangxi Province were determined by the co-effects of structural and random factors, but the random factors played a more important role. The contents of TN and AN were basically the same in the spatial distribution, which were much higher in the north area than those of south area by using ordinary kriging interpolation. The regression analysis results showed that soil parent materials, soil types, topography, soil erosion, straw returning pattern, farmland use types and nitrogen fertilization rates had very significant impacts on spatial variation of soil TN and AN (P<0.01). Soil TN and AN contents showed significant negative correlations with elevation and river dynamic index (P<0.05). The soil parent materials were able to independent explain 6.1% and 4.1% of soil TN and AN spatial variation, and the independent interpretation ability of soil types to TN and AN spatial variation was 4.2% to 4.7% and 3.1% to 4%, respectively, and topographic factors explained 4.2% of TN variation and 2.8% of AN spatial variation. Soil erosion explained 6.2% and 3.5% of soil TN and AN spatial variation. Straw returning pattern explained 4.2% and 3.3% of spatial variation of TN and AN, respectively. Farmland use types explained soil TN and AN spatial variation by 2.9% and 2.0%, respectively. The independent explanatory ability of nitrogen fertilizer application on spatial variation of TN and AN were 18.8% and 5.6%, respectively. Thus, the straw returning pattern and annual nitrogen fertilizer application rates were the main factors in controlling the spatial variation of soil nitrogen in Jiangxi Province.