Polymer flooding is a widely used chemical Enhanced Oil Recovery (EOR) technique that can decrease water-oil mobility ratio and thereby enhance sweep efficiency. Accurate simulation of polymer flooding in porous media relies on an integrated characterization of polymer properties, especially the rheological behavior of polymers. The objective of this study is to accurately model and predict the shear-thickening and shear-thinning behavior of polymer injection in multi-permeability porous media by incorporating conventional core analysis, fluid analysis, bulk rheology test, injectivity test and coreflooding experiments. The study began with an integrated fluid and reservoir rock characterization. Injectivity tests and coreflooding experiments were then conducted, including polymer flooding in a core plug. The pre-constructed polymer coreflooding simulation model was history matched with experimental results and uncertain parameters were calibrated by optimizing key indicators reflecting polymer non-Newtonian behavior in porous media. The calibrated model was then used to model the polymer in-situ rheology and EOR performance in a heterogeneous core plug. In this investigation, A polymer that has both shear-thickening and shear-thinning features was modeled and calibrated step by step based on experimental results. This methodology is instrumental in advancing our understanding of the mechanisms behind the non-Newtonian flow behavior of polymers in Darcy-scale porous media.