Motor bus unitary body with large-sized rectangular tube underframe

The invention relates to a motor coach unitary body of a large rectangular pipe under frame, which comprises the under frame, an upper part body frame connected with the under frame and a coping, and a floor bracket arranged on the under frame; wherein, the under frame consists of a front overhang, a front axle, a front wheel casing, a middle section, a rear axle, a rear wheel casing and a rear overhang which are sequentially connected with each other; the upper part body frame comprises a front and a rear circles as well as a left side and a right side circles; the under frame is connected with the front and the rear circles as well as the left side and the right side circles of bodywork and the coping by connecting points to form a whole carrying framework, so that a plurality of closed stress ring structures are formed. The invention has the characteristics of strong collision-resistant and side rollover resistant capability, low cost, light weight, high adaptability, good safety, etc.