The modified poly(vinyl butyral) (PVB) hollow fiber membranes are fabricated via wet spinning method for the ultrafiltrations of bovine serum albumin (BSA) and humic acid (HA) solutions. The morphologies, dynamic contact angle, static adsorption, permeation performance and mechanical properties of the membranes were also characterized. The results indicate that with the addition of oxidized multi-wall carbon nanotube (O-MWCNT), the surface hydrophilicity and pure water permeation fluxes (PWFs, J(w)) of the modified PVB membranes are evidently improved. The modified PVB membrane (M-4) containing O-MWCNT has higher permeation flux than that of the bare membrane (M-2) without O-MWCNT in the ultrafiltrations of BSA and HA solutions. Furthermore, the membrane of M-4 has a lower flux reduction ratio (RFR), a higher flux recovery ratio (FRR) than that of M-2. After ultrafiltration, the fouled membrane of M-4 is easily regenerated. The Darcy's Law analysis illustrates that the PVB membrane (M-4) containing O-MWCNT has much lower permeation resistances than M-2 due to hydrophilicity increasing and protein adsorption decreasing. Additionally, the mechanical properties of modified PVB membranes are evidently improved after embedding O-MWCNT. (C) 2014 Elsevier B.V. All rights reserved.