The rapid development of nanomaterials and nanotechnology provides the water treatment new opportunities. MoS₂, as a graphene-like two dimensional(2D) nanomaterial, has attracted much attention due to its unique 2D sheet structure as well as physical and chemical properties. In this paper, we review the applications of 2D MoS₂ and its composites on adsorption, membrane separation, catalysis, antibacterial, and detection applications in water treatment area, of which adsorption and membrane separation are highlighted and discussed to achieve the goal of high removal efficiency of ions, dyes, antibiotics, bacteria and many other environmental pollutants. In the end, the applications of MoS₂ and its composites in water treatment are evaluated, and their potential development and faced challenges are discussepd, hopefully to be a novel nanomaterial and technical strategy to solve water environmental pollution and water resource shortage problems.