The invention provides a preparation method of a super-hydrophilic organic membrane. The method comprises the steps that firstly, a substrate with a micro-nano surface structure is provided and fixedto a smooth flat plate, and the surface of the substrate is coated with a release agent; secondly, a membrane casting solution is provided and cast on the surface of the substrate and stands still, and a layer of membrane casting solution membrane is formed; thirdly, the flat plate with the membrane casting solution membrane and the substrate are placed in a gel bath to form an organic membrane with a complementary micro-nano structure on the surface; fourthly, polymethacrylic acid macromolecules are grafted on the surface of the complementary micro-nano structure of the organic membrane by means of plasma-induced graft polymerization, and a modified organic membrane is obtained; fifthly, the modified organic membrane is soaked in a silica nanoparticle suspension which has amino functionalgroups and has the surface modified by a silane coupling agent. The surface of the prepared organic membrane is provided with the multi-level micro-nano structure, has super-hydrophilicity, high fluxand lasting pollution resistance, and has good application prospects in the field of membrane water treatment.