The s-shaped cylinder series post-treatment includes DOC component, DPF component, mixer, SCR component and thermal insulation component.With compact structure, high conversion efficiency, low back pressure, easy maintenance and low operating cost, it can effectively remove CH compounds, particulate matter and nitrogen oxides in engine exhaust.The mixer component can provide good ammonia distribution uniformity to ensure that the conversion efficiency of each catalyst meets the requirements and effectively avoid urea crystallization.The thermal insulation parts ensure the working temperature requirements of the internal catalyst, prevent the surrounding electrical components from high temperature damage and personnel safety protection.