Firstly

this paper studies sameness and differences of VNGIS(Vehicle Navigation Oriented Geographic Information system) and geographic information system.Automatic generation road center lines algorithm based on road inner-outer contour is presented.Then the paper mainly focuses the research of the study of double rectangle template track single road inner-outer contour and generate its center line. one template apply to track road inter-outer contour line

and at the same time triangle network is generated; the other judge if the current position is crossroad.In the end

the paper describe that the center lines of the whole road network are automatically generated when traversing.Road-segment list is created

and through modifying the list

road network is traversed.Experiences show; the arithmetic speediness、precision and sureness acquire road center-lines.