With the development of the automobile industry and economy, the automobile penetration rate is increasing. Most people are more concerned about the driving comfort of a vehicle, and the quality of suspension system directly affects the stability of a car. Although active suspension offers better control, its complexity and high cost limit its use to premium cars. And most regular saloons, the mainstay of the market, employ passive suspension. Therefore, the optimisation of passive suspensions remains important and marketable. In this paper, Matlab/Simulink is used to model the suspension as it relates to road inputs and the vertical vibration of a 1/4 vehicle with a dual mass. A three-factor, four-level orthogonal test was carried out on various models and road surfaces. The damping coefficient of the shock absorber, spring stiffness, and tyre stiffness were predicted by plotting line graphs, observing the pattern, and carrying out ANOVA using statistic package for social science (SPSS). The simulation results demonstrate that, while maintaining the stability of the suspension structure, a large damping coefficient, as well as small tyre and spring stiffness, effectively reduces the root mean square (RMS) value of body acceleration, suspension dynamic deflection, and RMS value of wheel dynamic load. This achieves a smooth and safe ride. Finally, it has been confirmed through a real vehicle test that reduced stiffness in the small tyre effectively lowers the body acceleration.