Abstract: FriedelCrafts acylation reactions of polysulfone (PSF) membrane material were conducted in the presence of Lewis acid catalysts at room temperature using two kinds of ωchloroacyl chloride, chloroacetyl chloride and chlorobutyryl chloride, and chloroacylated polysulfone (CAPSF) were prepared. The chemical structure and composition of the product were characterized by FT-IR, 1H-NMR and Volhard methods. The reaction processes on the chloroacylation reactions of PSF were primarily investigated. The experimental results show that the chloroacylation reaction of PSF can be carried out successfully, and a product CAPSF with a chlorine content of 0.5 mmol/g can be obtained in 3 h at room temperature (25°C) with CH2Cl2 as solvent and SnCl4 as Lewis acid catalyst. The experimental results also indicate that chlorobutyryl chloride is better than chloroacetyl chloride in the chloroacylation reactions.