Geographic Information System has made great progress in theory and technology in recent 60 years. The application field of GIS has expanded to all aspects of society, and the social influence is increasable growing. The architecture, development mode and service mode of GIS have undergone profound changes. In order to promote the further development of GISystem, this paper focused on the following three issues based on summarizing the three meanings of "S" in "GIS", namely "System" "Science" and "Service", and the fruitful achievements of "GIS" in recent 60 years. The first issue is how to understand GISystem. This issue should be analyzed from two aspects, and one is to discuss the connotation of geographic information system through analyzing the three key words (namely system, information and geographic) of GIS. The other one is to analyze the relationship between GIS and map, computer mapping and map database. This paper holds the idea that GIS originates from and goes beyond map, computer mapping and map database. It should be considered that GIS has the characteristics of equipment. The second issue is how does GIS evolve. This issue focuses on the social demand background, technical background and discipline background of the development and evolution from "Geographic Information System" to "Geographic Information Service". It also focuses on the main manifestations of the development and evolution of GIS from the aspects of application field, expansion of data resources and functions, architecture, development mode and service mode. The third issue is where will the future development of GIS go. We discussed that the limit application domain expansion of GIS and point out that the future development of GIS must face the urgent needs of national economic construction and national defense construction. Based on the analysis and comparison of three existing GISystem service modes, we consider that the "hybrid" technology system of "grid integration" and "elastic cloud" is the best choice for GISystem service mode. Finally, this paper puts forward six key technical problems that must be solved in the implementation of "hybrid" spatiotemporal big data platform technology based on "grid integration" and "elastic cloud"and designs the application mode of "spatiotemporal big data platform".