Aiming at the fault of the actuator leakage and the torsion fracture of the seal ring of an aircraft main landing gear,a two-dimensional axisymmetric model of O-shaped rubber seal ring (O-ring for short) was established using the finite element analysis software ANSYS.The effects of different fit clearance,groove depth,groove width,cylindricity and partial load on sealing performance during the assembly stage and the static pressure stage were analyzed.The results show that in a certain range,the fit clearance,groove depth and width have a great impact on the sealing performance,while the cylindricity and partial load have a small impact on the sealing performance.Within the allowable range,smaller fit clearance,appropriate groove depth and width can obtain excellent sealing performance.The reason for the leakage and torsional fracture of the O-ring of the actuator is that the sealing groove width is too large.In comprehensive consideration,the sealing performance of O-ring can be effectively improved by improving the width of sealing groove.