Abstract: The method of raster filling for the establishment of polygon file is a geogra-phical data processing method, which is based on the "spreading" algorithm of rasterpixels searching for the polygon outline automatically from the "inner point". This me-thod can be applied to any complicated polygon (such as that with "enclaves", or "holes",etc.). This software has been successfully applied in the relational geographical database software system (RGDBS), whch was developed by the author. This paper gives abrief description of the basic principles and algorithm concerned.