The Carbon emission trading mechanism is an important tool to tackle climate change, promote low-carbon economic development, and facilitate ecological civilization construction. The Carbon emission trading system is set up based on the overall amount control. It controls the greenhouse gas emissions through the marketing mechanism, and reduces the cost of carbon emission control. Through theoretical analyses of the property rights of carbon emission right and the legal relationship of carbon emissions trading ,the theoretical basis for the carbon emissions trading mechanism is established. Currently, the measures to improve the carbon emissions trading mechanisms in China mainly consist of perfecting the trading platform, improving the marketing regulation system, promoting legislations of the total amount control of carbon emissions and the initial allocation of carbon emissions right so as to realize the optimal environmental capacity allocation of carbon emissions.