In the process of polymer flooding in daqing oilfield, there are some problems such as water consumption growing tensions, sewage treatment increasing more differences and the problem of injecting sewage becoming serious. Using the produced sewage instead of water to dilute polymer solution flooding will be widely attached. Aiming at the characteristics of polymer flooding sewage depth by polymer flooding sewage and sewage water quality analysis, polymer flooding sewage by oxygen exposure and sterilization was used to study flow characteristics and oil displacement effect. Results show that, compared with deep treatment sewage, residual resistance coefficient with polymer solution is high after polymer flooding sewage dilution, the ability to reduce water phase permeability is enhanced, and recovery factor is improved. Under the same conditions of permeability, molecular weight, concentration, and depth of sewage displacement effect of polymer solution is not ideal compared to dilute oil, and the value of recovery efficiency  differs by about 1%. The same effect with the polymer flooding deeply produced by sewage dilutes can be achieved if the concentration of polymer solution diluted by the polymer flooding sewage is increased.