In BDD algorithm for network system reliability, there exist some repeated and redundant items after the network system is transformed into a binary tree. It affects the efficiency of searching disjointed minimal path sets. In this paper, a recursive BDD algorithm is presented, which contains two binary trees. One is the binary tree including a pseudo leaf node. The other is the BDD corresponding to the pseudo leaf node. Both theoretical analysis and instance computing show that the binary tree from RBDD has fewer levels and simpler structure than that from BDD, which effectively degrades the repeat and redundancy of the algorithm and improves the efficiency of indexing the disjointed minimal path sets.