Farmland grade is a basic index to evaluate farmland quality, and also a basis to establish the standards of land use tax, land compensation fee and land tenancy fee. MAPGIS software is effective in processing the spatial data and the attribute data, which not only can improve the speed and accuracy of grading, but also can reduce the workload greatly. This paper focuses on farmland grading of Huzhu County in Qinghai Province based on MAPGIS software, the technology of MAPGIS applied in farmland grading is summarized, the main steps are discussed, such as the establishment of farmland grading database, the partition of evaluation units, the acquirement of attributive data and the index calculation, the application of MAPGIS technology in the county farmland grading was explored and the questions that should be paid attention to in the county farmland grading were put forward.