EGR is the acronym of Exhaust Gas Recirculation system which is used for cooling of exhaust gas recirculation in engines with European emission level III or above. Because of high temperature, exhaust gas in the engine exhaust gas recirculation must be cooled fully in the EGR cooler and then directed together with charge air into the gas cylinder for further combustion. This can effectively restrain NOX production, save energy and reduce emission. The main body of the EGR system is made of such metal materials as stainless steel and castings. The products can be classified into water-cooled exhaust gas and air-cooled exhaust gas and with such structures as plate fin type, tube shell type, assembly type and other types. The products feature compact structure, diversified types, high temperature resistance, corrosion resistance and good performance. With the exhaust gas recirculation system, the products are one of the effective means for control of diesel automobile emission.