A rebar shear comprises a rebar shear body, a screw rod, a hanging buckle, a hanging buckle seat and a clamping and hanging device. The clamping and hanging device comprises clamping plates, a nut and clamping columns. Two clamping plates are connected to the end of a handle arm of the rebar shear body, and a hanging clamp is arranged at the upper end of the other handle arm. One end of the screw rod is movably connected with the hanging buckle seat, and the nut is mounted at the other end of the screw rod. The hanging buckle seat is connected with the hanging buckle. The clamping columns on the two opposite edges of the nut are clamped in clamping mouths of the clamping plates. When a rebar is sheared, the nut is clamped in the clamping plates, the clamping columns are clamped into the clamping mouths, and the hanging buckle is hanged on the hanging buckle. A shearing plate is clamped on the rebar, a user holds the handle arm where the clamping plates are located with one hand, and pulls a crank to rotate with the other hand, so that the two handle arms are folded to cut and the rebar. When the rebar shear is stored and folded, the hanging buckle, the screw rod and the nut are taken down, the rebar shear is folded, the hanging buckle is hung on the hanging clamp, so that the screw rod and the nut are hung at the side edge of the rebar shear. The rebar is sheared by adopting a mode that a screw rod and nut speed change device is connected to the upper ends of the two handle arms of the rebar shear, the labor intensity of a worker is reduced greatly, and the working efficiency is improved.