Aimed at the problem of the local excessive deformation in rubber and local tearing failure of a saddleshaped rubber sealing ring with steel ring or metal spring used in lock ring type fast opening blind cover in natural gas filter，an improved saddleshaped sealing ring was presented,which has the feature of floatability and adopts an outside metal ring to prevent rubber extrusion. The numerical simulation analysis was conducted on the sealing performance,the features of floatability and preventing rubber extrusion of the new sealing ring by using the FEA software ABAQUS.The results show that the sealing ring has the advantages of good sealing performance, and can effectively reduce the stress level of the local area to prolong the service life of the rubber sealing ring.The feature of floatability can greatly reduce the resistance to open the door lock ring after unloading.The friction state of the rubber ring is improved by the form of outside metal ring, and the rubber material extrusion is effectively prevented.