It should provide drivers with good operating condition and comfort working environment; It should isolate vibration, noise, waste gas and harsh climate and provide passengers with comfort riding environment; It should keep the completeness of cargo and make them easy to load and unload; The structure of body and its equipment should ensure the safety of driving and reduce the influence of an incident. The reasonable outer shape of body can effectively steer the surrounding current and should improve the dynamic characteristics, fuel economy and driving stability. It should also improve the cooling condition of engine and ventilation inside the cab