World Wide Web Geographical Information System(WebGIS) is the combination of Internet/Web technologies and Geographical Information System,it makes the web publishing and sharing of geospatial information in the whole world possible and has bought great influence to the national economical development and our everyday life. The paper first analyses the problem existed in WebGIS, and then introduces the Scalable Vector Graphics,in short SVG, which is a standard of file format for describing 2D graphics on Internet, recommended by W3C. Considering the trait of SVG, the thought for constructing WebGIS based on SVG is presented, and then the method of coding the geospatial data and attribute data with SVG is gived, the system architecture of WebGIS based on SVG is described, the method in developing GIS's function using Adobe's SVGViewer 2 0 plug-in in client side is also discussed. The thought gived in this paper is proved feasible and effective with an experiment system. The author believe that with more research on WebGIS based on SVG,SVG will play greater role in publishing geospatial information, futhermore, the geospatial information web sharing will become easier.