A system reliability estimation method for spatial jacket platforms is developed in this paper,The jacket platform is modeled into three-dimensional assembly of spatial beam and plate elements in Fi-nite Element Method(FEM).The limit failure states correspond to collapse of a series of structural mem-bers which are identified by engineering design criteria.In this paper the following aspects are taken intoaccount:the punching shear and buckiing failures in member failure modes for the tubular joints and tubu-lar columns respectively;incremental loading approach for establishment of the safety margin equations ofsystem failure;the algorithm of enumerating significant failure modes for the structural systems and otherconcepts,such as the false failure mode and the virtual limit state.The final work is devoted to the reliabili-ty analysis for a practical jacket platform presently put into operation on the Bohai Sea.The computed re-sults shows that method suggested in this paper is feasible and effective for A system reliability estimation method for spatial jacket platforms is developed in this paper, The jacket platform is modeled into three-dimensional assembly of spatial beam and plate elements in Fi-nite Element Method (FEM). The limit failure states correspond to collapse of a series of structural mem-bers which are identified by engineering design criteria. this paper the following aspects are taken intoaccount: the punching shear and buckiing failures in member failure modes for the tubular joints and tubu-lar columns respectively; incremental loading approach for establishment of the safety margin equations ofsystem failure; the algorithm of enumerating significant failure modes for the structural systems and otherconcepts, such as the false failure mode and the virtual limit state. the final work is devoted to the reliabili-ty analysis for a practical jacket platform presently put into operation on the Bohai Sea.The computed re-sults shows that method suggested in this paper is feasibl e and effective for