Abstract: Based on the theory of magnetic dipole and the influence between adjacent chains, a microstructure model of double-chain dipole for magnetorheological fluid was established. The shear yield stress equation of magnetorheological fluid was derived from the perspective of magnetic dipole energy. The influence of shear angle on shear force was obtained by the double-chain dipole model. The shear yield stress of magnetorheological fluid with different mass fractions (40%–70%) of carbonyl iron powder was calculated by the double-chain dipole model. The influence of magnetic particle mass fraction on the shear yield stress of magnetorheological fluid was analyzed , and was compared to the calculation by the single-chain dipole model and the test results. The results show that the simulated shear force of the double-chain dipole model basically first increased and then decreased with the increase of the shear angle, and reached the maximum value at a shear angle of 15°. The shear yield stress of magnetorheological fluid obtained by single-chain dipole model, double-chain dipole model and experiments all increased with the increase of carbonyl iron powder mass fraction. The average relative errors of the calculation of the single-chain and the double-chain dipole model were 97.51% and 29.58%, respectively. The double-chain dipole model could accurately simulate the shear yield stress of magnetorheological fluid under magnetic field.