As a new pathway to remove fixed nitrogen from marine ecosystem, anaerobic ammonium oxidation （anammox） widely occurs in various marine environments including the oxygen minimum zones, sediment, sea ice, even the deepsea hydrothermal vents. Anammox is a key pathway for accurately estimating nitrogen budget and plays a significant role in the marine nitrogen cycle, which has an important impact on the global climate change. The history of anammox study is discussed. In addition, the distribution of anammox rates in oceanic OMZs and sediments and its significance is also discussed. The major environmental factors affecting the anammox rate are also summarized, including temperature, oxygen, sulfide, NO^-₃/NO^-₂，NH⁺₄ and organic matter. Finally, the problems and challenges in present and future studies are suggested as follows: the relative contribution of anammox and denitrification in nitrogen loss in the OMZs; anammox in coastal hypoxic waters; further study of anammox in continental shelf and deep oceanic sediments; reevaluation of marine nitrogen budget.