The work aims to prepare an oil/water separation copper mesh in simple method of solution immersion. Copper mesh was soaked in sodium hydroxide and potassium persulfate solution to prepare superhydrophilic and underwater superoleophobic strainer mesh. Morphology and composition of the substrate were analyzed using scanning electron microscope (SEM) and X ray diffractometer (XRD), respectively. Its wettability was measured by contact angle meter. Cu(OH)2 of micron structure was produced on the surface of copper mesh. The contact angle between water drop in air and the surface was 0°, for oil drop in water, 159°. Therefore, the copper mesh exhibited superhydrophilic property in air and superoleophobic property in water. Oil/water separation experiments showed that the oil/water mixture containing gasoline, hexane, etc was separated effectively by the copper mesh at ambient temperature and atmospheric pressure, the separation efficiency was over 90%. After several days of seawater immersion, the copper mesh exhibited very high oil/water separation efficiency and good corrosion resistance to seawater. Superhydrophilic and underwater superoleophobic copper mesh prepared in the experiments can separate oil/water mixture and be applied to occasions of strong corrosion resistance.