Abstract: Copolymerization of dimethyl diallyl ammonium chloride (DMDAAC) and acrylamide (AM) was initiated by adding a NaHSO₃ solution to the reaction system that contained AIBA·2HCl initiator.By means of AIBA·2HCl-NaHSO₃ initiation system,a series of high intrinsic viscosity copolymers was prepared in water medium under different conditions.Effects of various factors such as mass fraction of monomer,mass fraction of initiator,pH of solution,the mole ratio of AM to DMDAAC and the feeding way of AM etc.were studied.The results indicate that the copolymerization can be initiated at low temperatures.At the conditions of 30℃,n(AM):n(DMDAAC)=4:1,ω(monomer)=30%,ω(AIBA·2HCl-RH)=0.01%,the copolymer obtained had a high intrinsic viscosity and yield.When the monomers solution was copolymerized at pH=7.0,the intrinsic viscosity of PDMDAAC-AM was 11.56 dL/g,while monomers DMDAAC and AM were copolymerized at pH=10.0,the intrinsic viscosity of copolymer was up to 13.60 dL/g.When the mole ratio of AM to DMDAAC was equal to 1:1,the cationicity and intrinsic viscosity of the copolymer were 38.8% and 11.61 dL/g,respectively,by adopting the continuous feeding way of AM.