In recent years, there have been frequent offshore oil spills, and the discharge of industrial oily wastewater has not been properly solved, seriously affecting biological and water quality, and people's requirements for water quality are getting higher and higher, so it has become increasingly urgent to find green and efficient technologies and methods for separating oil-water mixtures. In this work, glutaraldehyde, a widely used crosslinker, is used to graft natural polysaccharide chitosan onto PVDF membrane, which greatly enhances the hydrophilicity of PVDF membrane, and the superhydrophilic superoleophobic CG-PVDF membrane prepared can be used to treat oily wastewater. The materials for preparing membranes are inexpensive, easy to obtain, and environmentally friendly, recyclable, and will not cause secondary pollution. Therefore, this green and simple membrane separation method for the treatment of oily wastewater is of great significance in sustainable development.