In order to further understand the main factors affecting soil nutrients and the coupling between the influencing factors, this paper takes the Heihe River Basin as the study area and uses field sampling, experimental analysis, and geostatistical analysis to analyze the total carbon (TC) and nitrogen (TN) of the topsoils (0-20 cm). The spatial heterogeneity is studied, and the single factor and dual factor effects and applicable conditions of TC and TN are explored using the geo-detector model. The results show that both TC and TN are belonged to the normal distribution with medium variation, belonged to the first level according to the grading standard of the 2^nd national soil survey, in exponential interpolation models, and the interpolation are influenced by both the structural factors and random factors. The contents of TC and TN both show the decreasing trend from southeast to northwest, and the interpolation accuracy of TN is 0.71, higher than that of TC (0.55). The top three independent variables are soil organic matter(SOM) > bulk density(BD) >NDVI(normalized differential vegetation index) for TN explanatory and SOM > BD >EC(electrical conductivity) for TC explanatory, the interaction between SOM and other factors is mostly above 0.6. The areas where the maximum values of TN and TC contents of the soil appear are on the conditions of BD <0.6 g/cm³, EC in 0.3-0.35 µS/cm, pH in 7-8, SOM in 100-150 g/kg, particle size in 10-100 µm, TEM(average temperature) in -1-1℃, PER(annual precipitation) in 360-390 mm, TWI(terrain humidity index) in 6-9, slope in 15°-25°, NDVI in 0.95-1, aspect in north, and DEM in 2 500-3 500 m. It should be classified and managed according to the terrain, climate, vegetation and other factors for the improvement of soil quality.