Inaccessible pore volume and adsorptive retention exist when polymer solution flows in porous media. The influence of inaccessible pore volume was often ignored in previous studies of the seepage law of the polymer solution in porous media. With regard to this，the inaccessible pore volume of the polymer flooding，rheological curve and effective viscosity in the porous media of the polymer solution were determined through the experiment. Parallel capillary model was established considering the influence of the inaccessible pore volume. The effect of the inaccessible pore volume of cores with different permeabilities on resistance factor，effective viscosity，shear rate and depleted layer effect of the polymer solution was analyzed. Results show that the inaccessible pore volume derived from the cumulative polymer quality curve can be more accurate. The inaccessible pore volume can lead to lower resistance factor and effective viscosity and higher shear rate and depleted layer thickness for the polymer solution. The lower the core permeability is，the larger the inaccessible pore volume will be，and a larger error will be introduced to the calculation results of resistance factor，effective viscosity，shear rate and depleted layer thickness.