Based on the total nitrogen content data of 600 samples in Longxi County, the spatial distribution characteristics of soil nitrogen in Longxi County were studied by geostatistics and the nitrogen reserves were calculated. The results showed that the total nitrogen content in Longxi County was (0.734±0.306) g/kg, and the coefficient of variation was moderate. The average nitrogen density was 0.091 kg/m², and the nitrogen reserves were 7.6×10⁶ kg. The nitrogen reserves in the 0—10, 10—30, and 30—50 cm soil layers accounted for 35.97%, 7.06%, and 56.97% of the nitrogen reserves in the 0—50 cm soil layer respectively. The spatial distribution of total nitrogen content and nitrogen reserves in Longxi County was similar, mainly distributed in patches. The high-value area was mainly concentrated in Shouyang town and Heping Township in the south of the study area, while the low-value area was mainly concentrated in Guanjiawan Township in the east of the study area. From the vertical distribution, the total nitrogen content of soil decreased with the increase of soil depth. The total nitrogen content of 10 cm in the soil surface was extremely significantly or significantly correlated with latitude, elevation, slope direction, slope, rainfall, ground temperature, and air temperature. Principal component analysis showed that longitude, latitude, rainfall, ground temperature, air temperature, relative humidity, and evaporation could be considered as important environmental factors affecting the total nitrogen content of soil. Through clustering analysis can divide the Longxi County soil into five types. The total nitrogen content of class IV soil was significantly higher than the other four types of soil, and no extreme significant difference was observed among the rest four types of soil total nitrogen content. Soils contain total nitrogen content belong to the fifth class standard accounted for 70.35% of the total sample area.