To solve the problems of local overheating and excessive heat transfer to downstream which affects the performance of equipment of flexible bristle brush seal with large overfill structure,the heat transfer model of the flexible bristle brush seal with oil and gas two-phase sealing environment at the bearing cavity and the structural characteristics of the flexible bristle brush seal with large overfill was established and calculated.The real-time temperature of the flexible bristle brush seal plate and the temperature change of the flexible bristle brush seal were measured experimentally to study the temperature field distribution and heat transfer performance of the flexible bristle brush seal in oil and gas two-phase medium,and to analyze the influence of the working condition parameters and structural parameters on its heat transfer performance.The results show that the highest temperature appears at the contact between the rotor and the axial section of the brush bristle,there is a local high temperature in the axial section of the brush bristle area and no significant temperature changes in the radial region of the brush bristle,which illustrates the heat transfer mechanism of the flexible bristle brush seal with large interference structure.Increasing the differential pressure,speed,and media oil to gas ratio will lead to an increase in the outlet heat flow of flexible bristle brush seal.The differential pressure has the most significant effect on the outlet heat flow,so the multiple flexible bristle brush seals can be installed to reduce the outlet heat flow to suit the high differential pressure sealing environment.To reduce the outlet heat flow,a better range of structural parameters is obtained,which can provide a reference for the improvement of its heat transfer performance and structural optimization.