The utility model discloses a shredding cutter of a straw shredding and returning machine and relates to the field of agricultural machinery. The shredding cutter comprises a cutter shaft. Cutter bodies are evenly disposed on the outer periphery of the cutter shaft. Each cutter body is divided into a left part and a right part, the left part, the right part and a cutter handle form an inverted V shape, the body of each of the left part and the right part is crescent, the inner side of each crescent body is sequentially provided with a first edge and a second edge from the cutter handle end to a far end, and the tail end of the first edge is higher than the starting end of the second edge. The shredding cutter has the advantages that the shredding cutter is simple in structure, the shredding cutter includes fixed crescent blades, each left part, the corresponding right part and the corresponding cutter handle form the inverted V shape and are of an integral structure, assembling simpleness is achieved, each first edge and the corresponding second edge cut straw twice, good shredding performance is achieved when the shredding cutter is used for cutting hard straw and soft and tough straw, and thorough straw shredding is achieved.