The invention provides a special-shaped diversion device for a turning flood discharge groove and belongs to the technical field of drainage buildings. The special-shaped diversion device comprises aturning drainage groove and special-shaped flow guide structures which are laid at the cantilever sill of the drainage groove in a parallel mode. According to the deviation direction, the flow velocity and the flow state of the upstream incoming flow at the outlet of the drainage groove, the gaps of the special-shaped flow guide structures at the outlet of the drainage groove are distributed. Thespecial-shaped flow guide structures comprise semi-elliptical cylindrical pier bodies, middle pier bodies and folded-line pier bodies which are of integral structures. The semi-elliptical cylindricalpier bodies are distributed in front of sills, and the side views are in a right-angled trapezoid shape. The folded-line pier bodies are distributed on the sills and are in the same direction with thelongitudinal axis of the turning drainage groove. The middle pier bodies are connecting sections of the semi-elliptical cylindrical pier bodies and the middle pier bodies. Pier bodies are simple andconvenient to design and are easy for engineering construction. Pier heads are stressed simply, the pier bodies are attached to the drainage groove and the sills, and the pier bodies are stable in structure. When the discharged water flow is ensured to be uniform and smoothly introduced to the downstream, and also the energy of the discharged water flow is dispersed, so that the damage to the downstream riverbed and the bank slope is minimized, the downstream protection work is reduced, and the great economic benefits are brought.