By analyzing the content of all networks, the smart city visualization large screen system can timely discover and prevent the leakage of sensitive information that occurs on internal computers through the Internet, quickly locate and trace the source, and prevent violations; it can control the entire network and computer users Online behavior and network traffic are monitored to help the network operate efficiently, stably and safely, and provide effective technical support for information construction and management; the network attack situation is displayed intuitively, and the type and source of the attack are analyzed and displayed. The network security situation is clear at a glance.