Abstract: Polysulfone (PSF) membrane was modified using persulfate (K₂S₂O₈) as oxidizer, γ-aminopropyltriethoxysilane (KH550) as coupling agent, and amino silicone oil emulsion (ASOE) as grafting liquid. Factors affecting the membrane hydrophobicity, such as KH550 mass fraction, KH550 treatment temperature, KH550 treatment time, ASOE grafting time and ASOE grafting temperature, were investigated. Grafted PSF membranes were characterized by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) analysis, and the surface morphology after modification was visualized by Scanning Electron Microscope (SEM). Results show that the hydrophobic groups are successfully grafted onto PSF membrane surface. The membrane hydrophobicity is improved with the water contact angle increasing from 87° to 116°.