In order to effectively prevent scale formation in the polymer-contained sewage reinjection formation，it took the polymer flooding demonstration oilfield SZ36-1 oilfield as an example. The indoor compatibility experiment and core dynamic damage assessment，nuclear magnetic resonance spectrometer，environmental scanning electron microscopy and other analytical methods were used to compare the differences in scaling mechanism between polymer-contained sewage and conventional water flooding oilfield production sewage. The results showed that calcium carbonate scale occurred in reinjection water of SZ36-1 oilfield. The calcium carbonate scale in common sewage had a high degree of self-formation and was cubic with a particle size above 20 μm. The produced polymer in the polymer-contained sewage increased the degree of incompatibility，and matched and bonded with Ca²⁺ by —COO^-，which caused the deformation from multilateral crystal of calcium carbonate to spherical nanocrystalline calcite（<5 μm）. The scaling crystal adhered each other，and cross-linked with the incompatible product，such as suspended solids，formation particles，residual polymers，and so on，by which generating composite blockages. The reservoir damage degree of polymer-contained sewage scaling was greater than that of ordinary sewage. The composite blockages attached to the surface of mineral skeleton，filled in the intergranular hole or membranoid substance plugged the pore throat. The blocking was mainly occurred in large and medium hole throat，which increased the depth and complexity degree of formation damage. The research results had important reference value for the optimization of water quality index system in polymer flooding field，and provided theoretical basis for on-site regulation and controlling of polluted water quality.