Abstract: The marsh wetland is an important part of wetland ecosystems, which occupied a large proportion of the natural wetland area in China. As the source, sink and converter of nitrogen, its structure and function significantly affected the nitrogen cycle. The process of nitrogen circulation in marsh wetlands was summarized in different respects, including existence forms, input, immobilization, transformation and influence factor of nitrogen in marsh wetlands, and analysis was made of the ecological environmental effect caused by the nitrogen cycle. At last, a further research was prospected on the nitrogen cycle in marsh wetlands in the future.