Aiming at profile reversal during polymer flooding, in this paper, based on the geological conditions of a reservoir in the Bohai oilfield, the law of profile reversal during polymer injection with polymer viscosity was researched by investigating the diversion rate in low permeability layers with homogeneous polymer solution with different viscosity, furthermore, the oil-displacement experiments of slug combination were conducted with two heterogeneous polymers HPAM and HAPAM solutions with the concentration of 1500 mg/L and the viscosity of 30.5 mPa·s and130.8 mPa·s, respectively. The results showed that, with the increase of the polymer viscosity, the opportunity of profile reversal during polymer flooding became ahead of time, the diversion rate rose first and then fell, the peak value of the diversion rate in low permeability layers enhanced. Too high or too low viscosity was detrimental to enhancement of oil recovery. As for the Bohai oilfield, it was suitable to control the viscosity of the polymer solutions after across the embrasure within the range of 15—30 mPa·s. The profile improvement effect of the HAPAM solution with higher viscosity to multilayer heterogeneity reservoir was better than that of the HPAM solution with lower viscosity polymer; however, the injection pressure of the HAPAM solution was much higher than that of the HPAM solution. The alternating injection of high-low viscosity heterogeneous polymers had a more pronounced profile improvement effect for the multilayer heterogeneity reservoir offshore which was being implemented polymer flooding.