Abstract: Poly(diallylmethylbenzylammonium chloride)(PDAMABC) was synthesized using methylamine,allyl chloride,NaOH,benzyl chloride and 2,2'-azobis[2-(2-imidazolin-2-yl) propane]dihydrochloride as raw materials.The structure of PDAMABC was characterized by FT-IR,¹H NMR and elemental analysis.The viscosity behaviors of the polymer in sodium chloride,potassium chloride,potassium bromide,calcium chloride,magnesium chloride,magnesium sulfate and sodium sulfate solutions were investigated.The results show that the yield of diallylmethylamine increases from 72.79% to 83.41% by reusing the water phase and the collected distillate with low boiling point;the yield of diallylmethylbenzylammonium chloride is high and the product has a good water-solubility using the mixed solvents with a volume ratio in the range of 1:3~2:3 as solvents.The reduced viscosity of PDAMABC decreases with increasing the concentration of added salt.In 0.1 mol/L NaCl solution,it behaves as a polyelectrolyte with a mass concentration below 0.031 25 g/L,and a neutral polymer when the concentration is above 0.125 g/L.The influence order of added salts is as follows:Na₂SO₄< NaCl< KCl< MgSO₄< MgCl₂< CaCl₂ KBr.The shielding effect of anion to quaternary ammonium cation is the main reason for the decrease of reduced viscosity.