Abstract: A CDT-based determining method of topological relations for spatiotemporal regions was investigated. The following contents were especially studied， including CDT-based spatiotemporal region representation in static spatio-temporal database， the method of dividing the spatiotemporal region in simple polygon shape into conterclockwisely directed triangle， and determining method of these spatiotemporal regions in simple polygon shape in static spatiotemporal database. The results showed that five kinds of fundamental topological relations between spatiotemporal regions， i.e.， equal， contain， overlap， disjoint and meet， can be determined with CDT. The proposed method not only effectively realizes the variety of spatiotemporal data presentation and operation， but also avoids the effect of spatiotemporal data on efficiency when the spatiotemporal data were calculated on the basis of boundary coordinates directly.

Key words: conterclockwisely directed triangle, simple polygon, dividing a polygon into triangles, topological relation, static spatiotemporal relation