Constructed wetlands can treat various types of sewage and have good nitrogen removal capacity. With the deterioration of the environment, nitrogen emission requirements have also increased; how to maximize the nitrogen removal function of constructed wetlands is particularly important. Therefore, this paper aims to summarize the measures to increase the nitrogen removal capability of constructed wetlands. New nitrogen removal methods such as simultaneous nitrification and denitrification, partial nitrification-denitrification, and anaerobic ammonium oxidation are efficient ways to remove TN. The effect of nitrogen removal in constructed wetlands can be strengthened by optimizing the configuration, such as improving the water intake mode, optimization of substrate combinations, optimization of plant species configuration, and novel constructed wetland coupling process, and improving the operating conditions, such as adding external carbon sources, improving redox conditions, microbial enhancement technology, and aeration. On this basis, the mechanisms of nitrogen removal by microorganisms, substrates, and plants as well as the coupling roles played by each other in the process of wastewater purification are illustrated. This paper provides a systematic idea for increased nitrogen removal in constructed wetlands, provides some references for research in this field, and finally provides prospects for future research.