Eight terrain factors and five soil conventional nutrients were used as investigating data. Topographic factors were subdivided into five partitions by space grading statistics. Pearson’s correlation analysis was used to explore the typical relation model among five partitions. The similarity analysis between Pearson’s correlation of topographic factors and soil nutrients under distinctive sampling condition was conducted. Results showed that the similarity degree of Pearson’s correlation coefficients between topographic factors and soil nutrients reaches over 99% in different sampling schemes, which is the powerful proof of a characteristic relation model. The relation model of scheme C with 3 661 samples is the most similar to the characteristic relation model, suggesting that it is more rational and the evaluation method in this study is feasible and reasonable.