Multicast service with Quality of Service (QoS) guarantees is critical to many real-time multimedia internet applications.The QoS-aware multicast routing protocols should have the ability to find a sourced-based tree with the end to end QoS bounds and the minimal network resource consuming.The Delay Constrained Steiner Tree problem (DCST) is one of the key issues.We present the Branch Optimization algorithm for DCST.The core of our algorithm called Reverse Branch Adjusting Procedure (RBAP) is proposed to adjust the paths violating the delay constraint at the same time keep the modification to the spanning tree as little as possible.The simulation shows that our algorithm is efficient for actual networks.