Abstract:The objective and accurate study of comprehensive soil nutrients and their influential factors can provide reference for scientific fertilization of crops. The apple-planting area in Xunyi County of Shaanxi Province was selected as the study object. The comprehensive evaluation of projection pursuit was applied to comprehensively assess soil nutrients including organic matter, alkali hydrolysable N, available K and available P. The comprehensive projection index of soil nutrients was calculated according to the optimum projection direction. Soil nutrient level was evaluated according to the level of experience corresponding projection value. The spatial distribution of comprehensive soil nutrients was mapped by ordinary Kriging method and GIS, and the importance function of random forests was used to analyze the importance of influencing factors on nutrient contents. The results showed that the CPI variation in the study area was 0.653-1.516 with an average of 1.022, the variation coefficient was 14.746%, which was moderate. Moreover, CPI were in grades of III and IV. The spherical function was the optimal theoretical model by the accuracy of the cross-validation based on 80% training set and 20% verification set. The spatial distribution pattern of soil nutrients was as follows: except the high grades in Tuqiao, Zhitian, and the eastern part of Qiupotou towns, the integrated soil nutrient grade decreased from the west to the east in the study area, and the area ratio of comprehensive levels of soil nutrients from high to low was: 14.415 : 28.522 : 35.450 : 20.115 : 1.498. The comprehensive levels of soil nutrients were medium or low, and were mainly distributed in the eastern part. Soil nutrients were mainly affected by elevation, temperature and slope, and the influence degree of each factor varied greatly. The above results are consistent with the actual conditions in the area, thus can provide scientific bases for improving soil fertility of the local orchards and new ideas for comprehensive evaluation of soil nutrients.