Inspired by the hydration capability of hydrogel materials, cross-linked poly(N-acryloylmorpholine) (PACMO) chains were designed into poly(vinylidene fluoride) (PVDF) backbones to synthesize the copolymers (PVDF-g-PACMO) using the radical polymerization method. These copolymers were then cast into the porous membranes via immersion phase inversion. The effects of N,N'-methylenebisacrylamide (MBAA) in the reaction solution on the structure and performance of as-prepared copolymer membranes were evaluated by elemental analysis, X-ray photoelectronic spectroscopy, field emission scanning electron microscopy, water contact angle measurement, protein adsorption and filtration experiment. The grafting degree of PACMO increases with the increase of MBAA amount in the reaction solution, which endows the copolymer membrane with a good hydrophilicity. The protein adsorption and irreversible membrane fouling decrease and then further increase with the elevated grafting degree of PACMO. This result indicates that the anti-fouling property of membrane not only depends on the surface hydrophilicity and but also associates with the grafting structures of PACMO. This work provides a fundamental understanding of various grafting structures governing the performance of antifouling properties.