To improve polymer flooding results in Bohai heterogeneous heavy oil field，the dual parallel core flooding test was conducted to study effects of permeability differential，polymer concentration，water cut at polymer injection on the profile reversion，and effect of the injected polymer type and concentration，polymer alternative injection cycles on enhanced oil recovery was investigated. The results showed that polymer injection was suitable at early stage（water cut less than 80%）， small permeability differental（less than 6），and appropriate polymer concentration for effective mobility control and good injectivity had vital importance on polymer flooding efficiency. The alternating injection of weak polymer gel and polymer solution would reduce the total recovery at the same dosage of polymer injection；alternate injection of high concentration polymer system（2250 mg/L×0.15 PV）and low concentration polymer system（1750 mg/L×0.15 PV）for 2 cycles had more than 4.3% recovery efficiency than that of the direct polymer injection at the same dosage of 1200 mg/L·PV. The alternative injection of polymer slug could improve polymer flooding performance in Bohai heterogeneous heavy oil reservoir.