Poly(acrylamide-diallyldimethyl ammonium chloride-vinyl trimethoxy silane) [P (AM-DAD-MAC-VTMS)] was prepared by inverse free-radical emulsion polymerization technique. VTMS segment was hydrolyzed and condensed to form three dimensional networks. The effects of different factors, such as hydrophobic monomer feed ratio, cationic monomer feed ratio, pH value, and NaCl concentration, on decolorization efficiency were studied. Moreover, the decolorization mechanism was also explained by analyzing FTIR spectra and UV-vis spectra. The introduction of VTMS on flocculant enhanced removal efficiency of dye molecules. With the increasing VTMS, adsorption and net roofing-sweeping action of hydrophobically modified cationic polyacrylamide played the dominant role in the decoloring process of anion dye. VC 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 1602-1609, 2011