The invention discloses a tool for improving the smoothness of close-fitting holes. The tool comprises an oilstone clamp; one end of the oilstone clamp is connected with a hinge joint head; a bearingis fixed to the surface of the outer circumference of the hinge joint head; a connecting pipe is fixed to the outer circle of the bearing; a first rotating hole is formed in the connecting pipe; a rotating shaft is inserted into the first rotating hole; a rotating rod is rotationally mounted outside the connecting pipe; a mounting hole is formed in the end, close to the connecting pipe, of the rotating rod; a second rotating hole is formed in the side, close to the connecting pipe, of the rotating rod; the two ends of the rotating shaft penetrate through the second rotating hole to extend to the two sides of the rotating rod; and a connecting groove is formed in the end, far away from the connecting pipe, of the rotating rod. According to the tool for improving the smoothness of the close-fitting holes, the second rotating hole is formed in the side, close to the connecting pipe, of the rotating rod, and a universal mechanism is disposed between the oilstone clamp and the rotating rodso that the demand for grinding at different angles can be met, grinding is performed through equipment, time is shortened, the tool is autonomously developed, cost decreasing and benefit increasing are achieved, and the pioneering spirit of technicians of companies is enhanced.