Abstract. with the strict regulation of engine emission mandatory, the diesel engine exhaust emissions level put forward higher requirements, the domestic market sales of diesel engine must follow the upgrade. At present, Chinese has been in the country for the implementation of the national standards of vehicle emission regulations, with the engine at the same time, Beijing, Shanghai, the Pearl River Delta region has been implemented in the standard IV emission regulations, and soon in the nationwide implementation of China IV. For vehicle diesel engines, to achieve the National IV emission level technical route has two kinds, one is the use of exhaust gas recirculation EGR+ exhaust particulate trap, the other is the selective reduction of SCR exhaust emissions of processing. At present, most domestic and international automotive diesel engine enterprises adopt SCR technology roadmap to meet the requirements of National IV emission regulations.