As a kind of smart material, magnetorheological (MR) fluids are widely used in various engineering applications. Choosing an appropriate rheological model to describe flow behavior is crucial in the design of MR actuators. In this paper, the Herschel-Bulkley-Papanastasiou (HBP) model was first developed to fit the rheological properties of the MR fluid. The coupling modeling of the flow field and magnetic field of the radial MR valve were established, and the distribution of the magnetic field, velocity field, shear stress, and shear rate of the radial MR valve were also analyzed. The rheological properties of MR fluids and the inlet and outlet pressures of the MR valve were experimental tests. The experimental and numerical results indicate that the HBP model can better fit the rheological characteristics of MR fluids than that of the BP model, and the numerical results can better predict the magnetic field and flow field characteristics of the MR valve.