Wetland is the important part in urban ecosystem. Microorganisms is integral component of urban wetland ecosystem is the main factor of wetlands sewage treatment, and plays an irreplaceable role in the degradation. In this paper, the authors regard urban wetland of Harbin in north shore of Songhua river as the research object, through experiments to identify the microorganisms types, finding five microorganisms types being nitrify fungi. The article analyzes the contributions of microorganisms in nitrogen cycle of urban wetland. It is present that microorganisms plays an irreplaceable role in controlling pollutions and nitrification and anti-nitrification reactions play the most significant role in the degradation of nitrogen compounds and ammonium oxidation is a possible process in deducing nitrogen pollutions.

The global environment change is human beings are facing with the important and urgent environmental problems: in natural and human action double drive, the surface of the earth element biogeochemical process and its environmental effect is the current global change research in the area of the important content. In order to estimate and forecast geochemical cycle of change and to the global life support system influence, since the 1970s on the ecological system of the nitrogen cycle extensive and in-depth research, and in the process of this a series of ecological environment effect.Wetland biogeochemical process is refers to the carbon, hydrogen (water), oxygen, nitrogen, phosphorus and sulfur and various essential elements in the wetland soil and plant all kinds of migration between transformation and energy exchange process. Chemical process including nitrogen, phosphorus and other nutrients in the wetland system of flow and transformation, Wetland in heavy metals and other organic inorganic pollutants absorption, so close, transformation and enrichment, etc.