Abstract: The properties of metallic structural materials are governed by synergistic interactions between chemical composition and microstructural characteristics, making the elucidation of intrinsic structure-property relationships a pivotal scientific challenge. Conventional characterization methodologies exhibit inherent limitations, whereas synchrotron radiation technology has emerged as an indispensable tool for investigating microstructural-property correlations, owing to its multidimensional analytical capabilities. This review comprehensively examines the evolution trajectory of synchrotron radiation light sources and their advancing applications in metallic material research. Experimental evidence demonstrates that in-situ synchrotron radiation techniques—including X-ray diffraction, micro-X-ray diffraction, wide- and small-angle X-ray scattering, and computed tomography—enable real-time multiscale structural co-monitoring. These advanced methodologies facilitate precise characterization of fine microstructures, deformation mechanisms, strengthening-toughening mechanisms, and damage evolution, thereby providing critical experimental foundations for optimizing high-performance metallic structural materials such as high-entropy alloys, magnesium alloys, and titanium alloys. The commissioning and application of fourth-generation synchrotron radiation sources, combined with synergistic advancements in high-quality X-ray beams, multi-modal correlative techniques, and sophisticated data analysis methodologies, will substantially enhance the precision of microstructural characterization and deepen the fundamental understanding of deformation mechanisms and strengthening-toughening mechanisms in metallic structural materials. These technological breakthroughs will accelerate the research and development of high-performance metal materials.