Due to characteristics of highly nonlinearity and lowspeed region hysteresis of the magnetorheological damper, the classical mechanical model cannot be used to describe the mechanical properties of the magnetorheological damper effectively. Based on the nonlinearity double viscosity mechanical model, the nonlinearity double viscosity improved mechanical model was established by using polynomial and sinusoidal function respectively. The parameter identification of the experimental data was carried out to evaluate the accuracy, advantages and disadvantages of the two fitting methods. The research results show that the accuracy of the two fitting methods can reach above 0.99, but the mechanical model parameters based on polynomial are more, and the order selection is more complicated, but the sinusoidal function fitting can effectively solve such problems. MATLAB/Simulink was used to simulate the improved sinusoidal functionnonlinearity double viscosity mechanics model, and the results were compared with the experimental data. The comparative results show that the model can be used to describe the nonlinearity and lowspeed hysteretic characteristics of the magnetorheological fluid well, and it has the characteristics of fewer parameters, simple form and simple modeling method