An optical fiber transmission system was designed to implement the long-distance and real-time transmission of traffic guidance image data. To overcome the defects of traditional optical terminal machines,a complete system architecture was built according to the needs of the transmission system. The design ideas of a physical layer and a data link layer were analyzed based on Ethernet relative protocol, some design principles of the important modules were also given,then the memory addressing and bandwidth estimation were calculated in details. The test results show that the image data with a maximum resolution of 1 024 pixel×768 pixel, and refresh rate of 60 Hz can be transferred in a single optical fiber in real-time with a maximum transmission rate of 1.5 Gbps and the distance of 5-10 km. Compared to the original system,the proposed system reduces additional optical equipment and the fiber utilization rate is increased by 80%. Moreover,the cascade function of the receiver end has reduced the laying costs.With reliable performance, the system can implement the transmission task of real-time image data from a traffic command center to the guidance LED display in most of the cities.