Abstract: The research progress of the factors affecting the denitrification of constructed wetlands (CWs) and the measures to strengthen denitrification at home and abroad were reviewed. The nitrogen removal mechanism of CWs including plant absorption, substrate adsorption, and microbial ammonification, nitrification, denitrification and anaerobic ammonium oxidation were extensively illustrated. The effects of main influencing factors, such as influent carbon-nitrogen ratio, hydraulic retention time, plant species, wetland operation mode, temperature, pH and dissolved oxygen, on the nitrogen removal capability of CWs were also analyzed. Based on these analysis, the specific measures for advanced nitrogen removal of CWs including external carbon source addition, plant species optimization, new substrate application, artificial aeration and thermal insulation were introduced. Finally, the research and development directions on nitrogen removal in CWs were prospected.