Abstract: In recent years,aquaculture developed rapidly in coastal areas.Due to the feeblish inner sea water circulation-exchange capacity and the long-term accumulation of black-odor sediment,aquaculture water quality and sediment become to be deteriorated further.But this problem generally exists in enclosed or semi-enclosed water environment.So magnesium hydroxide was used as water quality and sediment amendments for the treatment of water environment.The progress of research and utilization of magnesium hydroxide perform as water quality and sediment amendments in the field of water environment were commented in this paper.The mechanisms of magnesium hydroxide using in water environment,including the electrostatic effect between magnesium hydroxide and suspended particles,the degradation of nitrogen and phosphorus by magnesium hydroxide,and the degradation of hydrogen sulfide by magnesium hydroxide were profiled.The application of magnesium hydroxide in mariculture areas,freshwater lake,water reservoirs,water bloom prevention and control,red tide prevention and control and wastewater treatment were outlined.Numerous applications showed that magnesium hydroxide could be applied to improve the water conditions of aquaculture area,freshwater lake,water reservoirs,water bloom,red tide and wastewater.Application trend of magnesium hydroxide and nano-magnesium hydroxide in the field of water environment was prospected.