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According to the test results of 6266 groups surface soil samples collected in Nankang area of southern Jiangxi, to achieve high-precision quantification of land quality geochemical evaluation coupling soil fertility and soil environmental quality, a cusp catastrophe model was established and applied to evaluate land quality geochemical evaluation. In this model, soil fertility index (Pf), including SOM, P, N, K, Mo, Mn, B, Cu, Zn in solid samples was the main variable, Nemerow index (Pn), including As, Hg, Cd, Pb, Cr in solid samples was the secondary variable, for values greater than 3 of Pf, Pf were revised to 3.1, and the influences of adjusting on the results were compared. The results showed that the average of Pf was 0.75 and the overall level of soil fertility was Ⅲ, the soil fertility was lower, the average of Pn was 0.59 and the overall level of soil contamination was cleaner. The linear relationship between the boundary value of soil fertility index calculated by the adjusting Nemerow index and the land quality grade was better. The results of comparing with DZ/T 0295—2016 showed that 83.57% of the evaluation grades were the same, and nearly 16% of the grade was increased by one grade, the range of grade increase or decrease did not exceed 1. The area of grade 2 was mainly distributed in the southeastern edge and the middle-northern part of the study area, the area of grade 3 was widely distributed, and the area of grade 4 was sporadically distributed. The research results showed that the method can be used for the comprehensive evaluation of land quality geochemistry, with more numerical and simpler evaluation process, it was a supplement to existing methods for comprehensive evaluation of land quality geochemistry which can provide effective reference.