Traffic signs model are very important for road BIM. In order to quickly build the BIM model of traffic signs, this paper studies the characteristics and rules of traffic sign design based on national regulation, analyzes the components of traffic sign layouts, and proposes the concept of "general word" for traffic signs. Applying the secondary development technology, the auxiliary software of BIM model for traffic signs is developed in Bentley platform. The software simplifies the traffic sign layout design, rapidly constructs the traffic sign library, applies the "general word list" to assist the establishment of the traffic sign layout mode, flexibly and efficiently establish traffic signs BIM model. This paper discusses the research process and implementation method of the software for traffic signs BIM model, and demonstrates the software functions. The results show that the software provides technical support for the rapid modeling of traffic signs.