Biphenyl polyimides, which are known by its excellent heat resistance and mechanical properties, were synthesized by adjusting the molar ratio of monomers, followed by end-functionalized with zwitterionic group via reaction with 1,3-propanesultone. The zwitterionic sulfobetaine biphenyl polyimide (z-biph-PI) copolymers with different hydrophobic chain lengths were employed as the additive for the preparation of polysulfone (PSf) membrane. X-ray photoelectron spectrometry (XPS) measurement on membrane surfaces revealed that the sulfobetaine groups of z-biph-PI migrated toward water in the membrane formation process, during which a large amount of porous, narrow and densely packed pores were created as illustrated in scanning electron microscopy (SEM) images. Therefore, the incorporation of z-biph-PI simultaneously enhanced the pure water flux and protein rejection ratio of membranes, overcoming the trade-off effects between permeability and selectivity. The adsorption of bovine serum albumin decreased from ∼47.7 μg/cm2 for the pristine membrane to a minimum of ∼12.4 μg/cm2 for the blend membrane. More importantly, the tensile strength and elongation at break were also simultaneously improved due to the unique mechanical property of biph-PI and the strong π-π interaction between biphe-PI and PSf. Meanwhile, the blend membrane exhibited excellent filtration and thermal stability. All these characteristics of the blend membrane made it promising in ultrafiltration application.