The present invention provides a porous membrane for water treatment, comprising: a high molecular weight polyethylene, a water-soluble polymer and an antioxidant, the high molecular weight polyethylene having an average molecular weight of 1.0×105 to 10.0×106 and a density of 0.940 to 0.976 g/cm3; wherein, the weight of the water-soluble polymer is 5 to 50 parts, the weight of the antioxidant is 0.1 to 10 parts, based on 100 parts of the weight of the high molecular weight polyethylene. The porous membrane for water treatment prepared by the present invention has a thickness of 5 to 30 μm, a pore size of 10 to 100 nm, a porosity of 20 to 60%, and a surface contact angle of 30° to 95°. The porous membrane according to the present invention has good durability, simple preparation process, and relatively thin thickness, a uniform pore size distribution and small pore size, good hydrophilicity, as well as good filtration and adsorption effect.