Abstract: This paper describes a distributed long tunnel monitoring system implemented using PLC and KingSCADA 6.52. The system structure, hardware design, and communication methods are detailed. CAN communication technology is used to achieve distributed communication between multiple PLCs, and Ethernet is used to communicate between the PLCs and the host computer. The software control part adopts component development technology, integrating the developed components into the configuration software to shorten development time. The system has been put into operation in the Yue Ma Chang Tunnel project in Wuhan City, with good application results. Keywords: PLC; Configuration software; Distributed communication; Component development Tunnels are now an important part of highway and urban road systems. Urban tunnels are characterized by high traffic volume, insufficient lighting, and poor air quality. Therefore, compared with ordinary road sections, accidents in tunnels are more difficult to handle due to limited space, leading to longer traffic interruptions. The danger is even greater in the event of a fire. Furthermore, due to their obvious low-lying characteristics, they are prone to water accumulation, especially during heavy rains. Therefore, the drainage system of tunnels is also of great importance. Therefore, the main purpose of establishing a tunnel monitoring system is to enable the system to monitor various environmental parameters of the tunnel in real time. Once an anomaly occurs, it can quickly detect the location and type of the anomaly, promptly identify and handle occasional accidents within the tunnel, and resolve traffic congestion caused by such accidents. Therefore, based on the above description, the basic structure of a tunnel monitoring system includes the following subsystems: lighting system, ventilation system, traffic guidance system, CCTV system, fire control system, emergency telephone system, broadcasting system, and drainage system. For details, please click: Tunnel Monitoring System Design Based on PLC and Configuration Software