The radial clearance is very important for the sealing performance of the floating ring,too large radial clearance causes the excessive leakage,and too small radial clearance leads to the grinding between the floating ring and the shaft under high temperature.The numerical calculation model of the mounted floating ring seal was established by using ANSYS Workbench analysis software,and the variation rules of radial clearance were analyzed by changing the structure parameters,operating temperature and sealing ring material.The results show that compared with the whole graphite floating ring,the mounted floating ring is more conducive to the adjustment of the radial clearance of the floating ring seal.The interference of the mounted floating ring seal has less influence on the radial clearance,but it can affect the striptemperature between the mounted ring and the graphite ring.The grinding between shaft and floating ring can be effectively avoided by selecting the mounted ring with large thermal expansion coefficient and the graphite ring with small elastic modulus.