Abstract: As the global “dual carbon” strategy advances, the world's energy structure is transitioning toward cleaner and lower-carbon sources. Hydrogen energy, as a zero-carbon clean energy source, is emerging as a vital component of future new energy systems. Utilizing existing natural gas pipelines for hydrogen transportation is widely recognized as a cost-effective and efficient solution for the large-scale, long-distance delivery of hydrogen. However, hydrogen molecules feature a small atomic radius and strong permeability, which readily induce failure mechanisms such as hydrogen embrittlement (HE), hydrogen-induced cracking (HIC), and sulfide stress corrosion (SSC). Such failure phenomena severely compromise the safe operation of hydrogen-transporting pipelines, representing the core bottleneck restricting the development of hydrogen-blended natural gas pipeline transportation. This study reviews the mechanisms of hydrogen embrittlement and its effects on pipeline materials, while systematically elaborating the latest research progress in key protective technologies. These technologies include the development of hydrogen embrittlement-resistant (HER) materials, advanced surface protection technologies and hydrogen trapping technologies via precipitate modification. Addressing these technical bottlenecks, this study aims to provide theoretical insights and technical support for the widespread repurposing of natural gas pipelines for hydrogen transmission, thereby facilitating the advancement of the global hydrogen energy industry.