Poly(ethylene glycol) acrylates (PEGA) containing double-bond in the molecular chain end were synthesized via the esterification of poly(ethylene glycol) (PEG) with acrylate acid in aid of the catalysis of p-toluenesulfonic acid. Then hydrophilic modification of poly(phthalazine ether sulfone ketone) (PPESK) ultrafiltration membranes was achieved by the Surface immobilization of PEGA assisted by UV irradiation. The Unmodified and modified membranes were characterized by Fourier transform infrared (FT-IR) spectroscopy, contact angle measurements, protein adsorption, tensile tests, ultrafiltration experiments. The results of water contact angle measurements and static bovine serum albumin (BSA) adsorption tests showed that the immobilization of PEGA afforded PPESK membranes to be more hydrophilic and less susceptible to protein fouling. The tensile strength and the break elongation ratio of the PPESK membrane declined in a small extent after the surface modification due to the cleavage of molecular chains under UV irradiation. From the comparisons of the pure water flux and PEG rejection between the unmodified and modified PPESK membranes, it was Suggested that water permeability and solute rejection ratio can be simultaneously promoted when controlling a fitting amount of immobilized PEG acrylates. The modified membranes have a good stability even when swelling in NaClO solution for a long time.