Prefabricated buildings are promoting building industrialization and low-carbon development due to their high quality, high efficiency and sustainability. The standardized design process and efficient design method are the fundamental ways to achieve efficient design of prefabricated buildings. In order to solve the problems of low standardization and limited design methods of prefabricated buildings, this study takes the prefabricated concrete composite wall-slab system (PCCWS) as an example and establishes a standardized design process for prefabricated components. Based on the Building Information Model (BIM) technology, a 3D parts library system was established using MATLAB software. The system stores the prefabricated components into the parts library, and the user can search, retrieve, and incorporate them. Taking a prefabricated dormitory project as an example, this study compares the design method of a 3D parts library based on BIM with the traditional design method. The preliminary findings show that the design method proposed in this study can improve the design efficiency by 42.9%. This study has practical significance for improving the design efficiency of prefabricated buildings and reducing production costs and provides a reference for the design method of prefabricated buildings.

Prefabricated utility tunnels combine factory production with on-site assembly to reduce on-site wet work and improve component quality and construction efficiency. Standardized design workflows and segment layouts coordinated with production, transport, and lifting conditions are essential for the practical application of integral precasting. To address insufficient coordination among cross-sectional dimensions, longitudinal segmentation, and assembly interfaces in utility tunnels with small and medium cross-sections, this study proposes a design method combining integral cross-sectional precasting with longitudinal segmentation. The workflow integrates cross-section definition, route segmentation, interface standardization, and feasibility checks. A keyway–bolt connection and composite joint waterproofing scheme are also proposed. Four drainage box-culvert types at Changsha Airport are used to illustrate the proposed design workflow. For a selected 50 m reach of the single-cell Type A culvert, the estimated cumulative on-site stage duration for the proposed precast scheme was 82.1% lower than the recorded cast-in-place total when curing-related waiting was included. The comparison assumes sequential on-site operations and excludes factory production and transport. The method coordinates component standardization with route adaptation and demonstrates potential to simplify on-site operations, providing a reference for the prefabricated design of utility tunnels with small and medium cross-sections and similar underground box structures.