The invention provides a straw crushing and field returning device. The straw crushing and field returning device comprises a bottom plate, a supporting device, a scraping plate device, a conveyor belt device, a rolling wheel device and a crushing device, wherein the supporting device comprises a first supporting pillar, a supporting platform, a second supporting pillar, a third supporting pillar, a fixed plate, a first bracket and a first transverse rod; the crushing device comprises a first frame body, a second frame body, a third frame body, first rolling wheels, second rolling wheels, first crushing teeth, a third rolling wheel and second crushing teeth; the scraping plate device comprises a second bracket, a first inclined rod, a scraping plate and a second inclined rod; the conveyor belt device comprises a cushion block, a first supporting rod, a second supporting rod, a third supporting rod, a rotating wheel and a conveyor belt; the rolling wheel device comprises a third bracket, a circular wheel, convex blocks, vertical rods and a horizontal rod; the third bracket is L-shaped; one end of the third bracket is fixedly connected with the upper surface of the third frame body and the other end of the third bracket is vertically downwards arranged. With the adoption of the straw crushing and field returning device, agricultural residues including straws and the like can be sufficiently crushed, and the generation of garbage and the combustion of the straws are reduced.