Abstract: Fatigue crack growth tests were carried out on X80 steel pipe joint samples at different loading frequencies (0.1, 1.0, 10.0 Hz) under nitrogen atmosphere, H₂+CO₂ atmospheres with the volume fraction of 2% and H₂+CO₂ atmospheres with the volume fraction of 5% and 2%, respectively. The effect of hydrogen content and loading frequency on fatigue crack growth rate was studied. The results show that when the loading frequency was 1.0 Hz, the higher the hydrogen content, the larger the crack growth rate of the joint base metal, heat affected zone and weld, and the increase degree of the crack growth rate of the weld was the largest. The fatigue crack growth rate of the weld was smaller than that of the base metal and heat affected zone under hydrogen atmosphere. When the hydrogen volume fraction was 5%, ductile fracture occurred in both the base metal and the heat affected zone, but there were small secondary cracks and a small number of platform structures on the fatigue fracture. The weld fatigue fracture had secondary cracks nearly 80 μm in length, but the fracture morphology was still mainly ductile fracture characteristics. When the hydrogen volume fraction was 5%, the fatigue crack growth rate of the base metal increased first and then decreased with the increase of loading frequency, and reached the maximum when the loading frequency was 1.0 Hz.