In the past two decades, research on CO 2 storage in coal seams and simultaneously enhanced coalbed methane recovery (ECBM) has attracted a lot of attention due to its win-win effect between greenhouse gas (CO 2) emission reduction and coalbed methane recovery enhancement. This paper presents an overview on the current status of research on CO 2-ECBM in the past two decades, which involves CO 2 storage capacity evaluations, laboratory investigations, modelings and pilot tests. The current status shows that we have made great progress in the ECBM technology study, especially in the understanding of the ECBM mechanisms. However, there still have many technical challenges, such as the definition of unmineable coal seams for CO 2 storage capacity evaluation and storage site characterization, methods for CO 2 injectivity enhancement, etc. The low injectivity of coal seams and injectivity loss with CO 2 injection are the major technique challenges of ECBM. We also search several ways to promote the advancement of ECBM technology in the present stage, such as integrating ECBM with hydraulic fracturing, using a gas mixture instead of pure CO 2 for injection into coal seams and the application of ECBM to underground coal mines.