With the rapid advancement of metro construction in China, the design process of fire alarm systems (FAS) still relies on manual operation, which is cumbersome and inefficient. Metro FAS design is gradually moving from two-dimensional computer-aided design (CAD) to three-dimensional building information model (BIM) to improve design accuracy and cross-disciplinary collaboration efficiency. In this paper, we propose a framework for the automatic wiring design of FAS in metro stations based on BIM. First, a wide variety of FAS devices and cable tray information is obtained through BIM to determine information about the layout, and loops are divided based on predefined rules. Second, since ring loops involve numerous devices, the Ant Colony Algorithm (ACA) optimizes connection sequences. For tree loops, devices are classified based on the presence of cable trays: if cable tray exist, devices connect to the nearest cable tray to minimize wiring usage; otherwise, the Minimum Spanning Tree algorithm determines the connection sequence. Then, the connectivity between the devices will be through an obstacle avoidance algorithm. Third, the study validates the feasibility of the proposed method through a real-world case study of a metro station in Fujian Province. The results indicate that the automatic design methodology can reduce wire length by 11.2% to 24.7%. This not only demonstrates the advantages of applying BIM in FAS design but also highlights its potential for enhancing intelligent design processes. Furthermore, the findings provide a solid research foundation for future advancements in this field.