The amphoteric hydrophobic association polyacrylamide (HAPAM), AA/ AM/ AMC8S/ DMDAAC, with hydrophobic carbon chain, sulfonic group and quaternary ammonium group was synthesized using AM, DMDAAC and AMC8S as monomers, the average molecular weight was 5.5×106, The structure was characterized by infrared spectrum and 1H-NMR. Based on the researches of monomer conversion and molecular weight, the optimum reaction conditions were obtained: ω(monomer concentration)= 30%, ω (initiator) = 0.1% (based on the total amount of the monomers), reaction temperature 55 ℃, reaction time 5 h and productivity 84%. At the same time, the results showed that when temperature was 80℃, viscosity reserved rate was more than 66%, salinity was 8%, viscosity reserved rate was more than 75%, shear-resistant time was 240 min, viscosity reserved rate increased. These performances were better than HPAM.