Poly(vinylidene fluoride) (PVDF) microporous membranes with antifouling property were prepared by argon plasma-induced grafting of poly(ethylene glycol) (PEG) onto the membrane surface, including the pore surfaces. The PVDF membranes were pre-coated with PEG in a PEG/CHCl3 solution. The microstructure and composition of the PEG-grafted PVDF (PEG-g-PVDF) membranes were characterized by attenuated total reflectance (ATR) FTIR and X-ray photoelectron spectroscopy (XPS). A moderate radio-frequency (RF) plasma power and plasma treatment time led to a high concentration of the grafted PEG polymer. The morphology of the modified membranes was studied by scanning electron microscopy (SEM). It was found that the flux of water decreased with increasing surface concentration of the grafted PEG polymer, while the pore size remained almost unchanged, Protein adsorption and protein solution permeation experiments revealed that the PEG-g-PVDF membranes with a PEG graft concentration, defined as the [CO]/[CF2] ratio, above 3.2 exhibited good antifouling property.