Abstract: Base-map database system is a small one which possesses some basic functoins of cartographic database. In order to meet reguirements of selecting bade-map produced by rari-ous of the themalic mapping,it supplies a serious of selection ways. By using a large number of bit-operations,the database strucure is active and flexible. The data which freguenly ex-change are stored in the main memory,so that the database can run guickly. The system is able to organize polygons and hierarchical relations between regions automaticaly,reducing works in daba capture.