The ultrafiltration membranes were fabricated by blending Pluronic F127 and polyethersulfone (PES). The fourier transform infrared spectrometer (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis results confirmed that Pluronic F127 could exist stably in blend membranes, and tensile test showed that the addition of Pluronic F 127 exerted minor effect on the mechanical properties of blend membranes. Differential scanning calorimetry (DSC) analysis results indicated that Pluronic F127 and PES were partially miscible. The separation performance of blend membranes under different pressures was investigated by changing operation pressure from 0.05 to 0.30 MPa. It could be found that the operation pressure had more favorable effect on the flux of blend membranes than that of PES-control membrane. In particular, all blend membranes exhibited lower membrane fouling resistance, especially lower irreversible fouling resistance, and higher flux recovery ratio. (c) 2006 Elsevier B.V. All rights reserved.