Abstract: Low cycle fatigue tests were conducted on X80 elbow steel under the conditions of no hydrogen charging and hydrogen charging. The Manson-Coffin model for X80 elbow steel was established, and the influence mechanism of hydrogen on the fatigue properties of X80 elbow steel was studied in depth by EBSD micro-characterization technology. The results show that hydrogen significantly deteriorates the fatigue life of X80 elbow steel, leading to a significant decrease in fatigue life at strain amplitudes ranging from 0.3% to 0.5%, and the maximum hydrogen-induced fatigue damage reaching 58.7%, which shows a high sensitivity of the steel to hydrogen embrittlement; The Manson-Coffin model reveals that the fatigue plasticity coefficient decreases by 52.5% and the transition life shortens by 52.3% after hydrogen charging，demonstrating that hydrogen mainly weakens the plastic damage resistance of X80 elbow steel; The distribution of KAM and GND at the crack tip exhibits significant gradient characteristics after hydrogen charging，and hydrogen accelerates the initiation and propagation of fatigue cracks by promoting the highly concentrated dislocation slip at the crack tip.