Abstract: This paper aims at data structure of line map symbols. Firstly, graphic composition pattern and rendering efficiency in three classic structures of line symbol which contained cell-cycle, line-type overlay and function method were analyzed. Secondly, a structure and storage method based on PostScript imaging model were proposed for uniformly describing control axis in line symbols. Thirdly, three types of strokes which contained color-stroke, cell-stroke and raster-stroke were designed. They supported the two composition model of cell-cycle and line-type overlay, and could design cartoon and artistic symbols. Fourthly, an object called decoration was brought to design complex line symbols such as scarp symbol, and a rendering style based on contour transformation was proposed to support half-line & half-area symbol design as well. Any line symbol was composed of path, stroke, decoration and contour transformation. Finally, a prototype system was developed to conduct the experiments of efficiency comparison and multi-media output. Experiments show that this structure can render line symbols efficiently by decomposing them. It supports complex line symbols design and can export map symbols to computer screen for display, web for transmission and paper for printing easily.