In this work, we presented a facile and novel strategy, chelation-assisted in situ self-assembly, to prepare the loose polyacrylonitrile (PAN)-based nanocomposite membrane for dye desalination. Based on the chelate reaction polyethyleneimine (PEI) with metal ions, an Ag+-PEI complex layer was deposited onto the hydrolyzed PAN surface. Then, the chelate complex layer was served as the templates to in-situ synthesize the vitamin E succinate (VES)-functionalized AgCl nanoparticles , which were uniformly distributed on the membrane surface and provided additional transport pathways for water molecules. The prepared nanocomposite membrane achieved the permeability of 106.4, 101.2 and 92.3 L M-2 h(-1) MPa-1, which was 20-50% higher in comparison with that of the pure Ag+ -PEI@HPAN membrane, with corresponding rejections of 99.2%, 99.5% and 99.8% to crystal violet, acid fuchsin and congo red solution at the concentration of 0.1 g L-1. Meanwhile, this membrane possessed a low inorganic salts rejection (6.2%, 9.6% 8.3% and 12.8% for MgCl2, NaCl, MgCl2 and Na2SO4) and good stability during the 60 h filtration of dye-salt mixture. We anticipate that this novel route could be applied to prepare the polymer-supported nanocomposite membrane with enhanced separation performance.