Exhaust gas recirculation method and system

The embodiment of the invention discloses an exhaust gas recirculation method and system.The method comprises the steps that when exhaust gas enters a gas inlet pipe of an engine from an exhaust pipe of the engine through a gas path pipeline of an exhaust gas recirculation (EGR) cooler, an ECU receives the real-time temperature sent by a temperature sensor of the gas inlet pipe in real time, wherein a water path pipeline of the EGR cooler is wrapped by a gas path pipeline; determining a real-time temperature control scheme according to the real-time temperature; and according to the real-time temperature control scheme, a valve of a waterway pipeline of the EGR cooler is controlled so as to control the flow of cooling liquid in the waterway pipeline, and then the temperature of the waste gas is controlled. The temperature of the intake manifold is controlled through EGR waste gas, most fuel can enter the air cylinder in a gaseous state, the mixing uniformity of the fuel and air is optimized, fuel wall attachm