Rear-mounted contrarotated rotary tiller

The invention relates to a rear-mounted contrarotated rotary tiller which comprises a gearbox, a hexagonal shaft, rotary tilling knives, a protecting cover and a rolling wheel, wherein the gearbox is fixed in the middle of the protecting cover, and the left side of the protecting cover is connected with the rolling wheel through a pull rod; the hexagonal shaft is fixed at the lower side of the protecting cover, a contrarotated driving wheel is sleeved at the middle part of the hexagonal shaft, two hexagonal sleeves are sleeved outside the hexagonal shaft, a rotary tilling knife disk is fixed on the hexagonal sleeves through screws, four mutually vertical rotary tilling knife sleeves are welded on the rotary tilling knife disk, the handle ends of the rotary tilling knives are sleeved in the rotary tilling knife sleeves, and a bend is arranged at the middle part of each rotary tilling knife. The invention has the advantages that because a contrarotation working mode is adopted, the penetrating angle of the kniv