In recent years, several research efforts have focused on the application of information technology (IT) as a means by which to improve the integration process of construction safety management. Visual representation can provide an effective tool for monitoring and management in the field of safety management. In Taiwan, monitoring of hazardous gas detection on the underground construction sites is a very important issue. In order to enhance the performance of controlling in hazardous gas detection in underground construction sites, this chapter proposes a solution for the integration of building information modeling (BIM) and wireless sensor networks (WSN) technologies to enable the monitoring of hazardous gas conditions in underground construction site and provides warning signals. WSN consist of small nodes with sensing, computation, and wireless communication capabilities. First, the proposed methodology is implemented by using BIM technology due to its capability to accurately provide visual safety-related status indications with different colors. Furthermore, in order to support the wide range of safety analysis used wireless communication capabilities, proposed BIM-based safety monitor system is developed. Thus, this chapter examines the use of the BIM-based safety monitor system to provide the flow of safety information collected by WSN sensors, and visually illustrates the status of detection and alarm regarding to hazardous gas with different colors. A case study is presented to demonstrate the applicability of the proposed approach. Finally, benefits, limitations, conclusions, and suggestions are summarized for further applications.