Taking the GIS developed by a gas company in Chengdu as an example, functions and applications of the GIS of city gas pipeline network are discussed. The unified GIS development platform is used to design and realise the synthesis of GIS based on B/S structure and mobile GIS. The sharing of resources is realized by means of the distributed data storage method. Functions of decision-making of rush repair, statistical analysis, decisions of patrol scheme of the gas pipeline are implemented. With the construction and application of the GIS, the different applications of the gas enterprise are satisfied, the informationization level is improved, and the efficient operation and management of gas enterprise are promoted. The safety risk is also reduced, thereby the emergency decision level of city public security is enhanced.