Alongside the increasing of CO2 released, greenhouse effect on earth became more and more serious over the past century, finally resulted in global warming and sea level rise. To solve the environment problems came from greenhouse effect, scientists around the world carried out many research projects on the globle carbon cycle. Compared with other continents such as Europe and America, East Asia may have more ecological importance in the study of global carbon cycle. In 2007, an international joint research project (the A3 Foresight Program), aiming to investigate the carbon sources and sinks in East Asia, was launched, which is founded by the national foundations of China, Japan and South Korea. To reflect the main outcomes in the past three years from this program, the journal Science China Life Science published a special issue "Carbon Budget in East Asian Ecosystem" in 2010 (Vol. 53, No. 7, 2010). This issue contains 14 contributions categorized into 4 parts, including carbon stocks and their regional variations, changes in carbon sources and sinks for different forest ecosystems, carbon stocks and changes in grassland and farmland ecosystems, and new approaches to carbon cycle research. The main points and significations of these articles are comprehensively commentated.