The in-line after-treatment includes DOC parts, DPF parts, mixer parts, SCR parts and thermal insulation parts.With compact structure, high conversion efficiency, low back pressure, easy maintenance, low operating cost, can effectively remove the ENGINE exhaust CH compounds, particulate matter and nitrogen oxides;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.It is widely used in the after-treatment system of light and medium cars.