Abstract: Taking a field of Yucheng City, Northeast of Shandong province, as our study area, this paper intends to research for quantitative methods for soil fertility evaluation. Based on the plentiful information that obtained by field-survey, soil sampling and lab analysis, the automatic and quantitative evaluation procedure was realized by adopting the improved Grey Relation Model and supported by GIS techniques. The Grey Relation Model was improved by utilizing analytics hierarchy process and fuzzy math. The area and spatial distribution information of soil fertility grades were acquired, and the results were consistent with local conditions according to field-survey and lab analysis. The approach was feasible and effective in soil fertility evaluation. This research contributes significantly to scientific management and sustainable use of soil resources and provides consults to improve soil quality.