In this study, hydrophilic sulfonated polysulfone (SPSf) was synthesized via direct sulfonation of polysulfone (PSf) and efficiently implemented as a hydrophilic additive to prepare the polysulfone/sulfonated polysulfone alloy membranes. On a basis of a high compatibility of PSf and SPSf, the effect of SPSf content in the casting solution on the structure and separation performance of the membranes was investigated. It was demonstrated that the SPSf incorporation could significantly change the hydrophilicity, porosity, morphology and the charge characteristic of the resulting membranes. Compared the pure PSf membrane, the membrane with SPSf 15% yielded an improved hydrophilicity (contact angle was lowered by 23%), more porous structure and more negatively charged surface. It exhibited a high pure water permeability of 2521.6 L/m(2)h MPa, excellent steady-state flux of 118.0 L/m2h and HA rejection of 86.8% when filtrating 10 mg/L humic acid (HA) solution in dead-end mode under an operating pressure of 0.08 MPa. In a real treatment of mariculture wastewater for 8 h, this membrane exhibited a significant improved steady-state permeation flux of 175.7 L/m(2)h, which was increased by 144% and 26% compared to those of the homemade and commercial PSf membranes, without any deterioration of the permeate quality. The current investigation indicated that the PSf/SPSf alloy membranes held a promise for the real application. (C) 2016 Elsevier B.V. All rights reserved.