Branched polyethylene glycol (PEG) was anchored onto a membrane surface by efficient covalent self-assembly to optimize the separation and antifouling properties of polyvinylidene fluoride (PVDF) ultrafiltration membranes based on its excellent hydrophilic and antifouling properties. The results showed that the surface self-assembly method could effectively improve the stability of PEG and the surface wetting ability of the PVDF membrane, and simultaneously enhanced the water flux and rejection of modified membranes. Meanwhile, the fouling results showed the anchored PEG segments on the separation interface contributed to improve the antifouling performance of the PVDF ultrafiltration membrane with significantly improved anti-adsorption capacity for bovine serum albumin (BSA) and expectant water flux recovery ratios for BSA and humic acid (HA), two typical pollutants. This paper provides a sample modification idea and demonstrated covalent self-assembly was an effective method for surface modification.