in this paper,an improved cut-based recursive decomposition algorithm is proposed for lifeline networks.First, a complementary structural function is established and three theorems are presented as a premise of the proposed algorithm. Taking the minimal cut of a network as decomposition policy,the proposed algorithm constructs a recursive decomposition process.During the decomposition,both the disjoint minimal cut set and the disjoint minimal path set are simultaneously enumerated.Therefore,in addition to obtaining an accurate value after decomposing all disjoint minimal cuts and disjoint minimal paths,the algorithm provides approximate results which satisfy a prescribed error bound using a probabilistic inequality.Two example networks,including a large urban gas system,are analyzed using the proposed algorithm. Meanwhile,a part of the results are compared with the results obtained by a path-based recursive decomposition algorithm. These results show that the proposed algorithm provides a useful probabilistic analysis method for the reliability evaluation of lifeline networks and may be more suitable for networks where the edges have low reliabilities. in this paper, an improved cut-based recursive decomposition algorithm is proposed for lifeline networks. First, a complementary structural function is established and three theorems are presented as a premise of the proposed algorithm. Taking the minimal cut of a network as decomposition policy, the proposed algorithm constructs a recursive decomposition process. During the decomposition, both the disjoint minimal cut set and the disjoint minimal path set are simultaneously enumerated.Therefore, in addition to obtaining an accurate value after decomposing all disjoint minimal cuts and disjoint minimal paths, the provides, approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate approximate based recursive decomposition algorithm. These results show that the proposed algorithm provide s a useful probabilistic analysis method for the reliability evaluation of lifeline networks and may be more suitable for networks where the edges have low reliabilities.