Abstract: Hydrogen-blended natural gas transportation can achieve low-cost, large-scale and continuous hydrogen energy supply. In a high-pressure hydrogen environment, the hydrogen atoms adsorbed on the pipeline surface will diffuse into the pipe interior driven by the concentration gradient, resulting in hydrogen embrittlement. The hydrogen embrittlement process of pipeline steel is complex. The steel grade, surface defects, microstructure defects, as well as the corrosion environment and operating conditions all affect the change law and mechanism of hydrogen embrittlement sensitivity. Exploring the compatibility characteristics between the current long-distance natural gas pipelines and the hydrogen environment is of great significance for preventing and controlling the occurrence of hydrogen embrittlement and ensuring the safe operation of hydrogen-blended pipelines. The sources of hydrogen and its permeation processes during hydrogen-blended natural gas transportation are briefly described, the main development history in hydrogen embrittlement mechanisms is summarized, and the effects of internal and external pipeline defects, service environments (hydrogen concentration, temperature, stress state), and alloying elements (copper, vanadium, molybdenum, and niobium) on the hydrogen embrittlement sensitivity of pipeline steel are analyzed emphatically. Finally, the future research directions on hydrogen embrittlement sensitivity of hydrogen-blended natural gas pipeline steel are discussed.