It is not easy for liquid cationic flocculant diallyldimethyl-ammonium chloride (DM) homopolymer to simultaneously exhibit both low viscosity and high polymer content, which limited its application in offshore oilfield. In this paper, sodium allylsulfonate (XS) and sodium formate were used in the aqueous solution polymerization of DM. An amphoteric flocculant (PDMXS) with the properties of high polymer content (about 55 wt%) and low viscosity (efflux time measured by an Apply 4 viscometer was less than 100 s) was prepared. The optimum reaction conditions were identified as follows: the mass ratio of XS/DM was 10wt%, the concentration of sodium formate was 2000 mg.L-1, reaction temperature was 55 degrees C, the concentration of KPS was 0.5 wt% and the reaction time was 4 h. The polymerization kinetics was discussed. The results showed that R-p proportional to [M](1.97)[I](0.68)[CTA](0.71) and the apparent activation energy was 72.55 kJ.mol(-1). (C) 2018 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.