The utility model discloses an oil tank foreign matter taking-out device for a transformer. The device comprises a rotationally connected connecting plate, wherein the tail end connecting plate is rotatably connected with a supporting plate, each connecting plate is wrapped in an oil-proof hose in a sealed mode, an electric walking device, a foreign matter searching device and a foreign matter grabbing device are installed on each connecting plate, and the electric walking device, the foreign matter searching device and the foreign matter grabbing device are in signal connection with the foreign matter taking-out control device. When the electric walking device walks in the oil tank of the transformer; the whole connecting structure of the connecting plate and the supporting plate can be bent; the specific position change of the electric walking device is adapted; the position of the foreign matter can be checked through the foreign matter searching device and the foreign matter taking-out control device, the foreign matter in the oil tank can be grabbed through the foreign matter grabbing device, the foreign matter is pulled out through cooperation of the connecting plate and thesupporting plate, disassembly-free and oil-drainage-free foreign matter taking-out is achieved, operation is easy, maintenance time is saved, and maintenance efficiency is improved.