The utility model discloses a gasoline engine EGR stratified charging system based on a drainage plate, and belongs to the technical field of engines. According to the gasoline engine EGR stratified charging system, an exhaust pipe is fixedly connected with an air inlet manifold through a by-pass pipe, an EGR valve, an EGR cooler and an EGR loop, airflow cavities on the air inlet side of a cylinder head portion are connected with airflow cavities of an air inlet flow splitting cavity portion respectively and correspondingly, air inlets of the cylinder head portion correspond to branch pipes of the air inlet flow splitting cavity portion, an air throttle valve is fixedly connected with an air inlet manifold hole through the air inlet manifold, and exhaust branch pipes of the exhaust pipe are connected with four exhaust channels of the cylinder head portion respectively and correspondingly. According to the gasoline engine EGR stratified charging system based on the drainage plate, the phenomena that exhaust gas and fresh air are mixed prematurely outside a combustion chamber, and are stacked and mixed after an air inlet valve is closed can be avoided, isobaric air intake of the fresh air and pressure can be achieved, the mixing degree of the fresh air and the waste gas is reduced, load control over an engine can be achieved, the circulation heat efficiency of the gasoline engine is improved, combustion with the high EGR rate is achieved, and fuel economy of the gasoline engine is effectively improved.