Permafrost, a product of cold climate, can be degraded by climate warming. Permafrost thaws lead to the melting of ground ice and the water subsequent drain away, this process removes the support of surface layer, and thus leads to thermokarst terrains including thaw slump, ground subsidence. Thermokarst terrains not only affect infrastructure engineering, they can also deteriorate vegetation growth and deteriorate ecosystem. The ground subsidence can further gradually form thermokarst lake. Thermokarst terrains directly change landforms, and they also have great effects on hydrology, as well as carbon and nitrogen cycle. The topic of thermokarst development and its impacts have created many concerns in the permafrost environmental science. The quantitative assessment of effects of thermokarst terrains on carbon cycle is a fundamental step towards to understanding the response of permafrost and its feedback to climate change.