The Map Solution (MS) function of ABAQUS software was used to perform finite element simulation analysis of 2K step seal.Through the restart analysis and the grid repartition technology,the problem of the computing interruption caused by the grid distortion was solved,and the convergence solution under the ultra-high pressure was obtained.According to the stress-strain cloud map and the contact pressure distribution curves of internal and external stroke under the fluid pressure loads of 14 MPa,28 MPa,35 MPa,42 MPa and 56 MPa,the influence of fluid pressure on the main stress,main strain and contact pressure distribution was studied,and the results with MS function were compared with the simulation results without MS function under high pressure condition (35 MPa).The reliability of the analytical large grid deformation problem was proved.The results show that under ultra-high pressure conditions,the maximum principal stress of the Step seal is concentrated in the contact area between the PTFE stepped ring on the air side and the piston groove and cylinder,and the maximum principal strain occurs at the unloading angle of the PTFE stepped seal ring.With the increase of oil pressure,the trend of contact pressure distribution curve changes obviously,and the contact pressure gradient near the air side decreases.Under the same fluid pressure,the contact width of the sealing face of the external stroke is greater than that of the internal stroke.