The digital platform business model offers opportunities for the construction industry to address the problem of extensive development by elaborately orchestrating a range of construction services to meet complex construction requirements. The presence of isomeric and coupling relationships between two construction services leads to alternative execution paths in the service network. However, the problem of generating a service network with alternative branches has been scarcely investigated. This study proposes a hierarchical task network (HTN) approach to address the service composition problem. Specifically, the approach performs a depth-first traversal search to address the isomeric and coupling relationships. A branch merging mechanism is integrated to eliminate repeated planning caused by equivalent planning nodes. The experimental studies demonstrate that the approach can generate valid and correct branches in the construction service network and that the devised branch merging mechanism can significantly improve the efficiency of the approach.