14 kinds of sewage with different water quality were used for the indoor fluidity experiments. The adverse impact degree of different sewage to the cores was classified into high, middle and low, according to the the permeability loss rate. The results show that the factors affecting the permeability loss degree of cores are as followes: suspended sediment concentration > oil content > salt?resistant polymer concentration > common polymer concentration. Sewage with higher residual salt?resistant polymer concentration has strong plugging capacity. For the cores with air permeability of 200 mD, when suspended sediment concentration is 10 mg/L and oil content is 10 mg/L, the polymer concentration of salt?resistant polymer flooding sewage should be controlled below 200 mg/L, while the polymer concentration of common polymer flooding sewage should be controlled below 300 mg/L, in order to ensure the low degree of the damage to reservoir caused by sewage reinjection, The results of this work has a positive effect on the reservoir protection and water quality index of salt?resistant polymer flooding sewage reinjection.