The invention discloses a parallel multi-head full-automatic reinforcing bar straightening and hoop bending device and a use method thereof. The parallel multi-head full-automatic reinforcing bar straightening and hoop bending device comprises a straightening rack, a guiding cylinder, a straightening cylinder, a traction wheel, a metering wheel, a hydraulic cutting mechanism, a material bearing frame, a clutch, a bending mechanism, a stretchable universal joint transmission unit, a center post front-and-back stretchable unit, an upper incomplete gear and a lower incomplete gear. The parallel multi-head full-automatic reinforcing bar straightening and hoop bending device and the use method thereof are suitable for straightening and hoop bending of cold-rolled and hot-rolled deformed bars and hot-rolled round steel. According to the parallel multi-head full-automatic reinforcing bar straightening and hoop bending device and the use method thereof, five stretchable universal joints are utilized to be connected in parallel, the five universal joints are driven to transmit power to a lower gear shaft through bevel gear drive of a main driving shaft, and high synchronism is achieved by combining the advantage of high precision of the incomplete gears; a shaft shoulder is arranged on a designed center post so that the phenomenon of clamping caused by entering of reinforcing bar oxide skin and sundries can be avoided. Whole equipment has the advantages of being low in use failure rate, low in energy consumption, free of damage to ribs, low in noise, little in vibration, efficient in application, reliable in operation, light, flexible, convenient to move and the like.