To improve a SUV’s ride quality and mobility, the SUV was modified using air suspension systems. An electronic control unit based on Freescale XDP512 microcontroller was designed including a minimum system, a speed signal conditioning module, an air pump control module, a combined valves control module, a body height measuring module and a CAN module, a body acceleration measuring module. The ANSI C code of the control strategy of the ECAS system was generated using Real Time Workshop(RTW) code generation techniques, and then series of experiments of the car body coupling with speed, cornering, accelerating, decelerating, ride quality were conducted. The results of the experiments showed that the newly designed ECU could effectively finish the following functions: vehicle speed signal conditioning, the coupling of suspension height and vehicle speed, the control of an electrical air pump and a combination valves, etc.