Nitrous oxide is an important trace greenhouse gas which also acts as an ozone depletory.Ocean is one of the main sources of N_2O in the atmosphere.The emission of nitrous oxide (N_2O) in the Marine environment is often considered to be the result of microbial activities such as nitrification and denitrification.Ammonia oxidation is the key step of nitrification,and ammonia oxidizing archaea is considered to be the main practitioner of ammonia oxidation process in ocean.In this paper,the distribution of N_2O,the elements affecting abundance of amoA from ammonia oxidizing archaea(AOA) and ammonia oxidizing bacteria (AOB),and the progress of N_2O foring mechanism by AOA and AOB are reviewed.Finally possible AOA and AOB and N_2O formation mechanism under back ground of global climate change,ocean acidification and extending of ocean OMZ are discussed.