Abstract: The purpose of the research is to study the factors that affect the comparability of farmland classification achievements at county scale and the methods to reduce their affection, to lay the foundation of the summary of the achievements at provincial and national scale. Results show that the equivalent value areas charts of climate or light-temperature productive potentiality by GIS technique, the sudden value change across the county boundary can be greatly eliminated. At provincial level, with a unitarily defined classification factors and their weight, by controlling and correcting the comparability of natural quality scores between sample area and targeted areas, the natural quality scores among the targeted area can be compared.In the calculation of production ratio coefficient, calculation based on the crop planting area is more reasonable than that based on the factor classified area. Based on the verifying and correcting the data investigated, with the reference of achievements in economic and agricultural regionalization, the result of defining the equivalent value area of landuse and land economic coefficient, then calculating the average value of the coefficient in each equivalent area is nearer to the reality than the coefficient calculated based on the administrative division. All the above conclusions lead to a better classification achievements compare among the counties and the direct classification achievements summary to the provincial scale.