Abstract: The fertility of cultivated land is all kind of factors of land ability in the certainty region for certainty land type. At present, the vector ways was used to evaluate the land fertility commonly and the ways of fuzzy clustering and principal component analysis were used as synthetical assessment ways based on the data base of land resource for county. Because there were a lot of vectors to overlay during this course, fragmental primitive would be produced and the value of grid data would be flattened. The Grid GIS would conquer such shortcoming. Taking the Grid as the basic assessing cell and taking the administrative cell as statistic cell, the paper evaluated the fertility of cultivated land in Yitong County. The results classified that, the land productivity of Yitong info five levels and coupled the environmental factors with land productivity. The results showed that, the arable land with better quality in Yitong County mainly distributed on the floodplain and lower terraces of rivers, which accounted for 82.12% of the total arable land. The low-yield arable land was mainly distributed in the hilly area. The results would offer the data support for plan, protect and rational use for land resource in the future.