With the advancement of society and the accelerated pace of people’s lives, our pursuit of quality of life is also increasing. The car is not an unattainable luxury for nowadays. Not only that, but we have higher requirements for the comfort and smooth performance of the car. This puts higher demands on the suspension system of the car, and the semi-active suspension emerges as an emerging suspension system. The most used damper in the semi-active suspension system is the magnetorheological damper, because it can adjust the damping force in time as the movement state of the car changes, so that it cannot only satisfy the comfort. Sexual requirements can also meet the requirements for smooth performance. Its emergence has aroused strong repercussions from the academic community and high attention from the industry. The medium of the magnetorheological damper is a magnetorheological fluid. By adjusting the input current, the intensity of the magnetic field is changed, and the consistency of the magnetorheological fluid changes rapidly, that is, between the Newtonian fluid and the solid. Reversible changes, and the response time of this change is only a few milliseconds, very fast. This provides an appropriate damping force in a timely and effective manner. The structure of the magnetorheological damper is simple, easy to operate, fast in response, and low in energy consumption, which is very promising. In this paper, the mechanical model of the double-tube shear valve type magnetorheological vibration reduction, the design, the particle swarm optimization algorithm and other parameters are analysed and discussed in detail.