The utility model discloses a speed changer end protecting structure which can effectively guarantee sealability, provide deformation allowance, enhance working stability of an engine and prolong service lives of the engine and a speed changer. The speed changer end protecting structure comprises a retaining plate gasket arranged between a speed changer shell and an engine shell, an engine shell inner compression edge and a speed changer shell inner compression edge are arranged on the engine shell and the speed changer shell respectively, the outer tops of a first ring portion and a second ring portion contact with inner side faces of an engine shell outer edge portion and a speed changer shell outer edge portion respectively, outer edges of the outer ends of the first ring portion and the second ring portion contact with outer side faces of the engine shell inner compression edge and the speed changer shell inner compression edge respectively, and the inner ends of the first ring portion and the second ring portion oppositely extend to form a tension inner ring. The speed changer end protecting structure has the advantages that the speed changer end protecting structure is high in sealability and has enough deformation space, automatic oil drainage can be realized, engine oil quantity in an oil bottom shell can be controlled, and carbon deposition rate can be lowered.