A RANS based shear stress transportation (SST) model was employed in this study to validate experimental results from a recent literature, which investigated the fully developed turbulent flow for a non-Newtonian shear thinning fluid, containing drag reduction polymer additives in a horizontal concentric annulus (inner to outer radio θ = 0.4). The polymer concentration varied from 0.07% V/V to 0.12% V/V and three mass flow rates from 3.92 kg/s to 5.95 kg/s were analyzed. The viscous property of the fluid was modeled by the power-law model. Simulation performed with the commercial code of ANSYS-CFX indicated that the SST model with default model constants overestimated the turbulence statistics of shear thinning flow in the near wall region where y+<60. As an effort to improve simulation accuracy, one of the model constants α1 was tuned in this study for the first time. Simulation results obtained from the modified model showed better agreement with experimental data compared to those from the default one. The present study represents a successful benchmark task for simulating turbulent shear thinning flow in concentric annuli with modified turbulence model constants.