In this paper, the modernization of GPS and the update research results of IGS (International GPS Service) are introduced. The main contents include the realization and maintenance of ITRF (International Terrestrial Reference Frame), the monitoring of the solid earth, earth orientation, crustal motion and sea level, the determination of scientific satellite orbit, and the application of GPS in atmosphere research and weather forecast. The main problems in GPS technology including the system bias to SLR, its own annual variety and the change of GPS satellite antenna phase center are also discussed.