The utility model discloses an 8-shaped forming device and belongs to the technical field of tunnels. The 8-shaped forming device consists of a workbench plate, a hydraulic arm, limiting plates, telescopic clamping plates, sliding 8-shaped sizing inner dies, limiting anti-floating clamping plates, a sliding formation outer die plate A, a sliding formation outer die plate B and a sliding inner die base plate. The 8-shaped forming device disclosed by the utility model has the characteristics that the yield is high, the production efficiency is high, the machining quality is good and the safe reliability is good.