<p>Hydrogen energy has attracted widespread attention due to its high energy density and environmental friendliness. However, the transportation of hydrogen is a key factor restricting its wide application. In recent years, pipelines are used to transport pure hydrogen or mixtures of hydrogen and natural gas. However, hydrogen atoms may permeate into the pipeline, causing hydrogen embrittlement or cracking. Preparation of a hydrogen barrier coating on the surface of pipelines is an effective method to solve this problem. In this study, Fe-Al coatings were prepared on X80 steel by pack aluminizing, and the effect of holding temperature on the morphology, thickness, and hydrogen diffusion coefficient of the coating was investigated. Microstructure analysis revealed that the Fe-Al coating consisted of a multilayer structure with FeAl₃, Fe₂Al₅, FeAl₂, Fe-Al, and Fe₃Al phases arranged from the outside to the inside. As the holding temperature increased, the thickness of the coating increased significantly, while the hydrogen diffusion coefficient of the coating decreased first and then increased. When the holding temperature was 800&#xa0;°C, the Fe-Al coating was uniform and dense, and no cracks and pores were formed in the coating. The Fe-Al coating prepared at 800&#xa0;°C exhibited the best hydrogen barrier effect, with the lowest hydrogen diffusion coefficient of 0.7206 × 10⁻⁷ cm²/s and the highest permeation reduction factor (PRF) of 8.32. This enhanced barrier property arose from the inherent alloy characteristics of Fe-Al intermetallic phase.</p>