The invention discloses a novel straw smashing and returning machine, and belongs to the technical field of agricultural machinery. The novel straw smashing and returning machine comprises a suspension bracket, a machine cover, a knife shaft side plate, a tensioning wheel, a case assembly and support feet; the left end of the case assembly is connected with a left second shaft, the right end of the case assembly is connected with a right second shaft, the other end of the left second shaft is connected with a drive pulley, and the other end of the right second shaft is connected with a drive pulley; the drive pulleys are connected with driven pulleys through belts respectively, the driven pulleys are connected with a left knife shaft and a right knife shaft respectively, the joint of the left knife shaft and the right knife shaft is provided with a support, and free-swinging knifes are arranged on the left knife shaft and the right knife shaft in a staggered mode; the front portion of the machine cover is provided with a transverse beam, a support frame and the support feet are fixed on the transverse beam, three sets of cut leaking preventing devices are connected to the support frame through bearings, and the left second shaft and the right second shaft are each provided with a protective cover. The novel straw smashing and returning machine is mainly applied to agricultural straw smashing and returning.