The utility model discloses a tool for overhauling under severe working conditions. The positioning device comprises a positioning sleeve, a clamp is arranged on the positioning sleeve; the lower endof the extension sleeve is fixedly connected with the clamp; the upper end of the extension sleeve is hinged with the handle body of the movable handle; one end of the movable handle is connected withthe upper portion of the U-shaped clamp, the lower portion of the U-shaped clamp is fixedly connected with the upper end of the pull rod, the pull rod and the extension sleeve are arranged side by side, the lower end of the pull rod is connected with the movable wedge, the pressing wedge is installed on the clamp and tightly attached to the movable wedge, and the movable wedge moves along with the pull rod to drive the pressing wedge to press parts. A traditional maintenance mode is changed, the valve element can be checked and replaced more quickly, operation is simplified, auxiliary work such as flushing cooling and drainage is omitted, operation safety is improved, and scalding accidents caused by high-temperature materials are avoided.