A set of floating ring seal floating performance test method was established by using eddy current sensor.The method can quantitatively determine the critical floating speed of floating ring seal,accurately measure the the radial displacement of the sealing ring,and obtain the variation curve of eccentricity of sealing ring with rotating speed by calculating.The experimental study on a specific floating ring seal used in aero engine was carried by the method under different operating conditions.The deviation between the measurement results of the radial displacement and the actual displacement meets the engineering test accuracy,which verifies the feasibility of the method.The test results indicate that the floating performance of floating ring seals is affected by the differential pressure and the sealing medium.When the floating ring seal operates normally,there is a fretting wear happened on the interface between the side face of the sealing ring and the end face of the seal casing.The effects of such a fretting wear on the overall performance and the service life of floating ring seals should be be taken into consideration when designing floating ring seals.