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