Electrically controlled air suspension （ECAS） has the function of adjusting suspension stiffness and body height， which can effectively improve vehicle ride comfort and handling stability. Taking a passenger car ECAS as an example， the viscoelastic damping characteristics of rubber airbag are described by fractional theory， and the thermodynamic model is optimized considering the equivalent damping and hysteretic characteristics， which is in good agreement with the experimental data， and the precision of the optimized air spring model is verified. On this basis， considering the longitudinal and lateral dynamic characteristics of the vehicle and the Dugoff tire model， a 14-degree-of-freedom vehicle ECAS dynamic model is established， and a Model Predictive Control （MPC） active suspension control method is proposed， with measurable variables as the input of the controller， to realize the active control under straight and turning driving conditions. Simulation and vehicle bench test show that the fractional correction model can well reflect the variable stiffness characteristics of ECAS， and the active suspension control strategy based on MPC can adjust the air spring stiffness in real time， control the body posture， and effectively improve the ride comfort and stability of the electric vehicle. The research method in this paper provides a new idea for vehicle suspension system modeling and active control.