Facing inereasingly stringent NO_x control requirements and the well-known drawbacks of NH_3-SCR technology, CO-SCR technology utilizes the CO inherently present in industrial flue gas from ferrous metallurgy, waste incineration, and similar processes as a reducing agent. It selectively catalytically reduces NO_x, simultaneously removing both NO_x and CO, effectively tackling issues of secondary pollution and high costs, and achieving waste utilization for pollution control. This approach offers significant environmental and economic benefits. Currently, research on CO-SCR technology has garnered widespread attention in the field of energy conservation and environmental protection. However, much of the research focuses on optimizing catalyst performance structures, with the underlying reaction mechanisms in various environments still not fully elucidated. Overall, the technology is in its nascent stages and urgently requires the development of highly elficient catalysts tailored for industrial usage of traditional precious metals while enhancing the simultaneous removal efficiency of NO_x and CO. Positive effects can be achieved through methods such as doping with transitional metals like Cu, Mn, Fe to induce synergistic elfects between metals, or by selecting suitable carriers and innovative structural systems. Furthemore, the catalyst's ability to maintain high activity under complex environments including oxygen-rich conditions, H_2O, SO_2, alkali metal poisoning, significantly affects its catalytic performance. Investigating the deactivation process through simulations of industrial flue gas conditions and utilizing in-situ testing, and other characterization techniques is crucial for studying catalyst resistance to poisoning. This review elucidates the fundamental reaction processes and challenges in practica applications of CO-SCR. It provides a detailed summary of the performance advantages and fabrication methods of three types of catalysts that are currently the focus of research. It analyzes the reaction mechanisms and approaches for mitigating catalyst poisoning under different reaction conditions. Furthermore, it presents prospects for the future development of CO-SCR catalysts. This research can offer theoretical guidance for developing more efficient industrial catalysts for simultaneous pollutant removal.