Abstract: The carbon budget of terrestrial ecosystem plays an important role in the global change,especially the forests as the principal part. Tropical forests have a lot of species and large biomass. It’s one of important factors that control the global carbon balance. Tropical rain forests cover 12% of the plant’s land surface, and they contain 40% of carbon in terrestrial biosphere. They become one of main factors to control the global carbon, balance. So, small change of this ecosystem may bring significant changes of the global carbon cycle. Recent years, some ecologists used eddy covariance to study carbon flux in tropical forests. Now, it’s a disputed question whether the tropical forest is a carbon source or a carbon sink. To a great degree, using fashion of tropical forest and forest fire are important factors that can decide the role of tropical forest. Many factors influence the accuracy of flux measurement, such as inaccurate flux measurement in the nighttime, horizontal and vertical flow. If we can decrease the measurement error in the most and improve our data analysis technology, we’ll know the role of tropical forest more accurate. It is a fact that the flux towers are very limited, for the whole tropical forests we can find out their important role through the calculated model. This paper presented some results of tropical forest researches. It’s good both for CO2 flux measurement and tropical forest research in our country.