Abstract: The vector-based method for generation of Voronoi diagram was analyzed at first. The drawbacks motived us to research the method which was suitable for GIS. In the paper, raster-based method for generation of Voronoi diagram was proposed at the first time. The key factor for it was distance transformation. Several methods using distance transformation were compared, the errors of which were also analyzed. At last the procedure for generation of objects's Voronoi diagram was introduced.