In view of the poor stability of polymers in high temperature，high salinity environment，the influence of AMPS，NVP and DMAM on the polymer viscosity，long-term stability，seepage characteristics and oil flooding effects were systematically studied under the class III reservoir conditions of Shengli oilfield. The results showed that the AM-AMPS/20%（20% was the AMPS dosage）solution performed the highest viscosity at concentration of 1500—3000 mg/L and at the temperature of 25—95℃ compared to polymer prepared with other AMPS content，and AM-NVP and AM-DMAM solutions. However，when the calcium and magnesium ion concentration increased from 874.0 mg/L to 5296.0 mg/L，AM-DMAM/10% solution became the best in viscosification. In terms of the effect of the monomer content，the higher the content of the AMPS monomer，the greater the viscosity of the polymer solution；and the opposite effect occurred when it came to the NVP and DMAM monomer cases due to the correspondingly decreased molecular weight of their polymers. The oil recovery tests showed that the AM-AMPS could enhanced oil recovery by 21.9%—24.9% based on the water flooding，while AM-NVP and AM-DMAM polymers could enhance oil recovery by 20.9%—19.8% and 21.1%—20.2%，respectively. AM-AMPS polymer had the strongest oil flooding capacity，among which AM-AMPS/20% performed the highest incremental oil recovery of 24.9%，which was promising to be used in class III reservoir of Shengli oilfield.