There are urgent requirements for data sharing on Earth System Science in China and abroad. How to build a scientific and universal data classification system is a difficult problem faced by Earth System Science data sharing because there are inherent characteristics of interdisciplines and integration. Firstly, the main international Earth System Science data classification systems are comprehensively analyzed in the paper. Global Change Master Directory (GCMD) classification architecture and its change trend from 2005 to 2013 are studied in detail. Then two typical classification features nowadays are pointed out, which are flat classification trend and bipolarity feature, i.e., super simple classification and super comprehensive classification. Online data services records of Data Sharing Network of Earth System Science (DSNESS), National Scientific and Technological Infrastructure, were calculated. High frequency visiting data sets and key words querying records were listed. Classification idea was produced with the combination of GCMD system and structural classification and DSNESS's user requirements and data services in practice. Data catalog system and keyword system are proposed finally. Data catalog system has 14 first class types and 173 second class types. Besides traditional sphere structure classification, new classification with China features are added to the data catalog system, such as typical region, nature resources, and so on. Keyword system includes 13 first class types, 71 second class types and 686 keywords. According to the service practice of DSNESS, serials of typical keywords are added to keyword system, such as typical natural region in land surface, ecosystem in biosphere, economic resources in human factor, nature resources, and so on.