On the bases of summarizing the functions, features and current status of digital map technologies, this paper analyzed the structure, technical workflow and characteristics of MGE digital mapping system. Then, the authors expounded some key technologies of MGE-based digital mapping system, such as data input and digitizing, color base and symbol base generation, map editing and color separation, as well as mutual conversion between printed maps and electronic maps. These technologies are very important to map designing, editing, plating, etc. Finally, the future of digital map integrated system are foreseen.