As the urban areas become denser, the built environment and land resources have limited the scope for further development of the urban areas. Haikou, as one of ten pilot cities to develop underground space, is chosen as the case in this study. Haikou Underground Pipe Gallery is a current underground building structure system that maximizes the utilization rate of land. This study investigates and analyzes the most useful and valuable technologies and systems of the Underground Pipe Gallery by survey and research. The result shows that U-shape construction technology is the most beneficial one and the electrical system is the largest and most widely used one. There are four high-tech applications in the electrical system: load power supply, construction of electrical distribution, power supply cable, and lighting facilities. In addition, a combination of green (sponge project), blue (water control) and gray (underground pipe network) infrastructure is utilized to create an optimal drainage system. It has made good use of the large area of urban green space and rainwater storage facilities.