1 Introduction With the improvement of the level of urban modernization, the construction of lighting night scenes has become an important symbol of the level of urban planning and construction. A beautiful city needs to watch the building for greenery during the day and the night view of the night. With its beautiful curves, the urban bridge has become an important landscape of the city. From ancient simple wooden bridges to modern large bridges with various structures, the bridges have been playing their unchanging role: connecting the traffic ties between the two places. However, with the development of economy and civilization, people have given more and more meaning to bridges. Therefore, in a sense, bridges are not only a kind of facilities, but also a medium for cities to convey economic development or artistic works. Become a designer's artwork. The city's cross-river bridge is an important part of road traffic. Its lighting is an important guarantee for the smooth and safe roads at night, meeting the illumination and uniformity required for the road bridge lighting function, and as an important landscape along the river, night lighting It should be ornamental and decorative, highlighting the beautiful appearance of the bridge itself, or giving the bridge a certain cultural content in the lighting combination, and at the same time echoing the water element to add more agility at night. 2 Basic principles for the design of lighting across bridges (1) Under the premise of ensuring the traffic function lighting of the bridge deck, do the night illumination of the bridge body; (2) Night lighting of river bridges as a supplement and enhancement of traffic function lighting shall not affect traffic safety, and shall not cause glare and light pollution to traffic, aviation, shipping, etc.; (3) The nightscape lighting of the bridge across the river should fully demonstrate the architectural style of the bridge, and highlight the characteristics and key parts of the bridge with lights; (4) Using a variety of light sources to form different levels of lighting landscape between the main body of the bridge and the bridge hole to enhance the artistic appeal and visual appeal of the structure at night; (5) The façade has a uniform or well-defined brightness distribution. Illumination in different orientations and angles causes different changes in illumination to enhance the overall three-dimensional sense; (6) Lighting facilities should be concealed as much as possible, without affecting the daytime landscape of the bridge; (7) Lighting facilities are easy to install and maintain; (8) Reduce engineering investment and operational energy savings. 3 Overall Planning and Design of River-crossing Bridges in Hengshui Section of Fuyang River 3. 1 Project background Hengshui is a rising garden ecological city in Jingnan. It is located in the southeast of Hebei Province, 250 kilometers away from Beijing. Hengshui in the Heilongjiang River Basin has a long history and profound cultural heritage. Hengshui not only has a profound cultural heritage and beautiful natural scenery, but also has a wonderful collection of traditional handicrafts that are amazing. The Fuyang River is the mother river of Hengshui. It stretches for thousands of years and runs through 13 kilometers (see Figure 1). It is an important planning project for the construction of an ecologically livable beautiful lake city. 3. 2 Lighting design principles and brightness grading planning refer to the "Urban Night Lighting Design Specification" JGJ / T163-2008, "Urban Environment (Decoration) Lighting Specifications" DB31-T316-2004 and the relevant lighting indicators provided by the International Commission on Illumination, and consider Looking at the influence of the distance, the reference brightness range is proposed. Table 1 divides the environmental area into three areas: E2 area, low-brightness area, equivalent to rural industrial or residential area, etc.; E3 area, medium-brightness environmental area, equivalent to suburban industrial or residential area; E4 area, high Brightness environment area, quite a city center and a business district. According to the relevant standards and norms, the night lighting illumination design of the cross-river bridge of Hengshui River in Hengyang City is designed as follows: (1) Brightness design is based on medium-brightness environmental area design standards in medium-sized cities. (2) Hue control: RGB LED full color conversion module. (3) Color temperature control: White light is selected as warm white color of about 3000K (see Figure 2). 
