A spatial data mining prototype system called Visual Geo-Classify System (VGCS) use to classify spatial data based on VC++6.0 is designed and developed. The authors used examples of data verified the effectiveness on system performance, algorithms and rules. The results indicate that this prototype system is a practical and extensible Visual Interactive Spatial Data Mining tool, it can achieve the interactive control of data mining course dynamic and real-time, the process and models of geo-spatial data classifying are visualized, and the results of data mining can be visual displayed, as well as visual thought, can be visual analyzed and can be visual evaluated.