The construction of China's carbon emission trading market has gone through a process from one-way participation in the international carbon market to voluntary emission reduction trading at home, and then to the total carbon emission right trading as the main and voluntary emission reduction trading as the auxiliary. The link of regional carbon emission trading system is conducive to reducing the cost of carbon emission reduction, promoting market liquidity, reducing operational risks of carbon market and reducing carbon leakage. The link of inter-provincial carbon market needs to break down administrative barriers and form a consensus on the link elements of carbon emission trading under the unified legal framework. The link of regional carbon emission trading system should be carried out from the aspects of legal mechanism construction, link mode selection and mutual recognition and assimilation of carbon emission trading system.