The invention provides a plastic corrugated pipe flexibility automatic detector for a prestressed concrete bridge. The detector comprises a detection pedestal and a movement module; the movement module is arranged on the detection pedestal; the movement module comprises a transverse movement module, a longitudinal movement module, a rotating module and a clamping piece; the transverse movement module and the longitudinal movement module are arranged to be stacked, the rotating module is arranged on any one of the transverse movement module or the longitudinal movement module, and the clampingpiece is arranged on the rotating module; by means of combination of the transverse movement module, the longitudinal movement module and the rotating module, the clamping piece can drive a corrugatedpipe to do left-right bending motion. According to the technical scheme, related provisions of JT/T 529-2016 pre-stressed concrete bridge plastic corrugated pipes can be met, flexible detection is conducted, the structure is simple, and the automation degree is high; the labor intensity of an inspector is relieved, and the batched detection is facilitated.