Abstract: In recent years, rainstorms have occurred frequently, urban waterlogging has intensified, and waterlogging of sunken bridge in Beijing is common, which poses a serious threat to people's lives and property. In order to guide the drivers and passengers to judge the dangerous situation on site and avoid the danger in time, based on the hazard degree of the water depth of the sunken bridges to the drivers and passengers, this paper designs a set of waterlogging warning sign system of the sunken bridges around the signs such as road guidance signs, water level warning signs and hierarchical layout of pavement markings. According to the hazard degree of water level of sunken bridges to vehicles and personnel, the risk level is divided into four levels, which are represented by red, orange, yellow and blue in turn, which are arranged in front, roadsides and road surfaces of sunken bridges. The warning sign system includes the water depth data and risk level of the position, which is conducive to the driver and passengers to observe the specific data of waterlogging depth and corresponding risks on site, avoid risks in time, and reduce the accident of sunken bridges during flood season.