This paper starts with study on the transfer characteristics, and the vibration isolation of the cab suspension. Vibration models of cab suspension and complete vehicle were built through multi-body dynamics software ADAMS. Finite element and multi-body dynamics were collaborated into the analysis of the transfer characteristics, the response and the isolation feature of cab suspension based on the complete vehicle. To improve the vibration performance of the cab suspension, improvements and optimization design were proposed with genetic algorithm method.The analysis results show that there only limited effectiveness on coil spring. So the improvement plans were proposed to replace the coil spring with an air spring and setting transverse damper. According to the plans, the original cab suspension was modified. The piecewise function method was used in fitting the characteristic of the air spring. This method can directly reflect the stiffness characteristic of the air spring within its working area, thus is good for the design and optimization toward different working stage. Meanwhile, the damping characteristic curve of the cab suspension was also designed.Based on the optimization of the modified suspension, there was a great enhancement on the vibration isolation. The lateral and vertical vibration of the seat sliding was decreased a lot. The result shows the optimization and the modification were effective and correct.