Semi-variogram model and ordinary Kriging interpolation method were used to analyse the spatial distribution and variation of the NO₃-N concentration based on 825groundwater samples collected from 2011 to 2014 in Jianghan Plain. Seven hydrological factors, including net recharge, depth to groundwater, hydraulic conductivity, vadose zone material, land use type, soil type, and soil total nitrogen, were used to predict the posteriori probability distribution of the NO₃-N concentration, where the contributions of these factors were calculated using Weights of Evidence (W of E) method. Results indicated that the NO₃-N concentration in Jianghan Plain followed the normal distribution after Box-Cox transformation. A spherical model was appropriate to evaluate the spatial distribution of NO₃-N concentration. The spatial correlation of the NO₃-N concentration existed within a range of 68.02km with the nugget/sill being 87.93%. The NO₃-N concentration showed that the higher values located in south region while the lower values located in north and west region. The area with the NO₃-N concentration exceeding 10mg/L accounted for 8.61% of the total area. In addition, the success rate curve indicated a good performance of the WofE model at a precision value of 0.91. The groundwater recharge indicated a positive relationship with the vulnerability to nitrate contamination as well as hydraulic conductivity and soil total nitrogen, while the groundwater depth indicated a negative relationship. When the lithology of vadose zone was sand and gravel, the type of land use was for the urban or construction, and soil type was alluvial, the aquifer was very easy to be polluted by nitrate.