Nitrogen, as the most demands of nutrient element for plants, can be uptake by the symbiosis of arbuscular mycorrhizal fungus (AMF) and host plant with different forms, such as inorganic nitrogen, simple amino acid, even some complicated organic nitrogen and so on. Since the NH+4 expresses low mobility in soil and AMF belongs to the obligate fungi, it can be accounted that AMF possess the major contribution for host plant about NH+4 uptake. Some recent researches showed the existing of ornithine cycle related to nitrogen transport in AMF, and the arginine may take the mostly nitrogen transfer role in the AMF hypha. In this article, we attempt to outline the mechanism of nitrogen metabolism such as uptake, transport, assimilation and exchange in AMF, and focus on the characteristic of AMF nitrogen utilization. Forthmore, we hope to elucidate why AMF take an important role in nitrogen cycle of the ecosystem.