Abstract: A new algorithm was proposed to solve two problems, complex reliability-calculating and large energy-consuming.Contrasted to the inclusion-exclusion principle, the algorithm generates fewer items and fewer arithmetic operations in solving the same problem.Numbers of new sub-nets generated during the process of disjoint and calculation.The sub-nets were used to calculate the reliability between the sink node and other nodes or to build the expression for calculating reliability.The structures of the new networks are simple and the reliability is easy to calculate.Finally, an example and complexity analysis demonstrate the feasibility of the algorithm.