Polysulfone (PSf) hollow fiber ultrafiltration (UF) membranes were surface-modified by the UV-induced graft polymerization of 2-acrylamido-2-methylpropanesulfonic acid (AMPS). Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscope (SEM) were employed to characterize the structural and morphological changes on the membrane surface. Water contact angle of PSf-g-AMPS membrane surface decreased to 15.45° when AMPS concentration was 2 wt.%, which was nearly 35° lower than that of the unmodified membrane. The results of streaming potential measurement at different pressures implied the negatively charged characteristic of the PSf-g-AMPS membrane. The flux of PSf-g-AMPS membrane increased about 60% as compared to original PSf membrane and the rejection of heparin sodium for PSf-g-AMPS membrane achieved 78%, which was about 4 times that of PSf membrane at 0.04 MPa.