The basic farmland information system (BETS) supported by geographic information system (GIS) was established, which could manage the data systematically and dynamically. With the BETS, a method in both quantitative and qualitative natures was developed to grade the farmland productive capacity. Evaluation factors were chosen, a hierarchic structure was constructed, single-factor evaluation models were built and the weight for each factor was calculated through correlation analysis, factor analysis, fuzzy evaluation, and hierarchic analysis respectively. The evaluation results indicated that the land productivity grade could be completely evaluated饰the natural factors of farmland today with the quick development of computer technique. The results, tested on the farmland of Gaoyou city, was shown to be more objective and more accurate, avoiding the defects of subjectivity just by the empirical methods and the blindness of pure mathematical methods.