Abstract: CO_x hydrogenation represents a key catalytic process for the high−value utilization of exhaust gases. The underlying reaction mechanism involves complex phenomena, including heat and mass transfer, surface reactions, and dynamic evolution between the catalyst surface and bulk phases. With increasing complexity in catalytic structures and industrialization of reaction conditions, traditional ex-situ or static characterization techniques have shown growing limitations in spatial resolution, temporal responsiveness, and reaction environment compatibility, making it difficult to gain deep insights into reaction intermediates, active sites, and structure-activity relationships. In recent years, the rapid development of multimodal operando characterization techniques has provided new tools for uncovering key structural features and reaction pathways in CO_x hydrogenation systems. These methods enable simultaneous signal acquisition under real or near-real reaction conditions, coupled with high temporal and spatial resolution, allowing researchers to systematically observe the dynamic behavior of catalysts from multiple perspectives—including gas-phase species evolution, electronic state changes at the catalyst surface, active site transformation, and overall structural stability. The coordinated application of multiple techniques is gradually overcoming the inherent limitations of single methods in terms of atmosphere adaptability, information dimensionality, and the ability to resolve dynamic structures, thus supporting the construction of structure–reaction–performance relationships in complex catalytic systems. Through techniques such as synchrotron vacuum ultraviolet photoionization mass spectrometry （SVUV−PIMS）, steady-state isotopic transient kinetic analysis （SSITKA）, infrared spectroscopy （IR）, angle and energy-resolved X-ray photoelectron spectroscopy （XPS）, in situ X-ray diffraction （XRD）, and Mössbauer spectroscopy, researchers are able to systematically and quantitatively analyze key features of catalytic systems—including composition, electronic structure, and kinetic behavior—under realistic reaction conditions. These insights help elucidate the transformation of reaction intermediates and surface segregation processes, providing a scientific basis for the rational design of highly selective catalysts.