Abstract: Using delimitating of the prime farmland based on the GIS spatial analysis technology and the farmland land quality evaluation results in the Yu Jiang County,Jiang Xi Province. On the Arcgis platform,farmland plots were chose as the evaluation unit,two evaluation factors included the farmland natural conditions and the farmland quality classification and grading results. Twelve indicators were slope,irrigation condition,drainage condition,soil type,organic matter content,effective phosphorus,rapidly-available potassium content,soil p H,soil erosion, farmland national natural grade,farmland national economical grade and farmland national utility grade. Based on these factors and indicators,this paper established the prime farmland delimitation model emphasis on the farmland quality. The evaluation results showed that the areas of the farmland evaluation scores which were higher than 85 were 28 775.32 hectares, these farmlands were delimitated into the prime farmland protection area and the prime farmland protection ratio was 80.06%.The GIS and the farmland quality evaluation results could provide scientific basis for the delimitating of the prime farmland.