Telescopic ruler for measuring short distance

The utility model discloses an extension scale for measuring a short distance, which comprises a first column body, a first slot is arranged in the first column body, a second column body is inserted in the first slot, one end of the second column body is positioned in the first slot and is rotatably connected with a gear, the slot wall of the first slot is fixedly connected with a first rack meshed with the gear, and the slot wall of the second slot is fixedly connected with a second rack meshed with the gear. A second inserting groove is formed in the second column body, a third column body is inserted into the second inserting groove, one end of the third column body is located in the second inserting groove and fixedly connected with a second rack meshed with the gear, scales are arranged on the surfaces of the first column body, the second column body and the third column body, and a limiting structure is arranged between the first column body and the second column body; in a normal state, the second col