Stable geometric chemical structures can ensure the long-term stability of separation membranes for water treatment. In this study, polydopamine (PDA)/polyethyleneimine (PEI) nanoparticle (PDA/PEI-NP) membranes are prepared using a vacuum-assisted self-assembly technique, in which PDA/PEI NPs are supported inside the polymer membrane. During the self-assembly process, highly adhesive NPs, which exhibit the formation of bonds, are selectively supported at the dead end of the membrane pores. This phenomenon inhibits the leaching caused by the fluid-induced erosion of traditional coatings. Therefore, the obtained membranes exhibit excellent long-term stability. Additionally, the membrane flux increases after modification because the NPs do not block the flow-through pores and the abundant hydrophilic groups decrease the threshold pressure across the membrane. The pure water permeability of the proposed membrane is 10,647± 49 L·m -2 ·h -1 ·bar -1 , which is 11.52% higher than that of the PDA/PEI co-deposited blank membranes. The proposed facile approach to develop stable and high-performance membranes is expected to facilitate the sustainable development of membrane technologies.