Abstract: To study the influence of the uneven distribution of magnetic particles on the mechanical properties of magnetorheological (MR) fluid, the chi-square distribution is used to simulate the uneven distribution of magnetic particles under the action of magnetic field, and the existing micromodels of MR fluid is modified. The effectiveness of the model is verified by the performance test of MR dampers. Based on the double chain micromodel of MR fluid, the hypothesis that the distance between adjacent magnetic particles is completely equal and does not change with the magnetic induction intensity is corrected, and chi-square distribution is used to describe the uneven distribution of the distance between magnetic particles. A distribution parameter is introduced to quantitatively describe the relationship between the distance of magnetic particles and magnetic induction intensity, and a modified micromodel considering the uneven distribution of magnetic particles is proposed. Based on the proposed model, the influence of the distribution parameter on the yield shear stress of MR fluid is investigated. The MR fluid modified micromodel proposed in this paper is introduced into the quasi-static model of MR dampers, and the maximum output of the damper under different currents is obtained. The effectiveness of the proposed model is verified by comparing with the performance test data of the MR damper. The results show that the micromodel considering the uneven distribution of magnetic particles can describe the yield shear stress of MR fluid under different magnetic inductions more accurately, especially in the case of low magnetic induction intensity, which can solve the shortcomings of the existing micromodels that overestimate the yield shear stress of MR fluid.