To understand the Earth system and improve the ability to deal with local, national, regional and global abrupt disasters and to resolve the issues such as resources and environmental problems and improve human health and welfare, by means of extensive international cooperation, the construction of a coordinated, comprehensive and sustained Earth Observation System is an effective approach. By introducing and analyzing the three Summits on Earth Observation held in recent years, Global Earth Observation System of Systems (GEOSS) is described, including its goal, extent, social benefits, technical methods and operative mechanism. One of key factors in successful construction of GEOSS relies on whether the participators can accept and implement the interoperability and consistent data standards to share data resources from global context or not.