Abstract: Global carbon cycle refers to accumulations and fluxes of carbon element in all spheres of earth surface system. Current global carbon cycle is apparently in imbalance, namely, it is unknown where part of carbon amount released from burning fossil fuels and destroying tropical forests is going. This is called as missing carbon sink. The studies have indicated that the terrestrial ecosystems of the Northern Hemisphere have accumulated the missing carbon. The origin of the missing carbon sin was reviewed as well as the major characters of terrestrial sinks and their affecting factors, and carbon sinks of China’s terrestrial ecosystems

Key words: carbon cycle, carbon sink, missing carbon sink, climate change, terrestrial ecosystems