The invention belongs to a device for eliminating a radial fit clearance, and in particular, a mechanism capable of eliminating the installation clearance of a displacement sensor. The device includesa first housing, a second housing, a piston rod, a displacement sensor, a sleeve, a wear reducing ring and an iron core; the left end of the second shell is embedded in the right end of the first housing; the piston rod is embedded in a cavity formed by the first housing and the second housing; the left end of the piston rod penetrates the first housing; the boss of the piston rod is located in the first housing; the right end of the piston rod is located in the second housing; the displacement sensor is disposed in the piston rod; the right end of the displacement sensor is fixed onto the right end of the second housing; the right end of the iron core is fixed in the sleeve; the sleeve is sleeved with the right end of the piston rod; the wear reducing ring is arranged in the left end ofthe displacement sensor; and the wear reducing ring is located between the displacement sensor and the iron core. The mechanism has the advantages of structural simplicity and convenient installation.Being additionally provided with the wear reducing ring, the mechanism can effectively eliminate the radial installation clearance of the sensor.