A hydrodynamic model of the sealing area and elastic leaf bending differential equations were established to study the leaf deformation and its influence on sealing performance.Through unidirectional fluidsolid coupling simulation and calculation by ANSYS,the effects of different working conditions and structural parameters on the sealing performance and leaf deformation were analyzed.The results show that the leakage and leaf deformation are increased linearly with the sealing pressure.Sealing pressure,leaf size and back plateleaf gap have greater influence on leaf deformation and sealing performance.The increase of the gap between back plane and rotor or leaf can appropriately increase leakage by greatly making the leaf ends float.