Abstract: The fracture toughness test of X70 steel pipeline under different hydrogen pressures was carried out by gas phase in-situ hydrogen charging method, and the change of fracture surface morphology was analyzed by scanning electron microscopy. The results show that when the hydrogen pressure was 0.6 MPa, the fracture toughness J₀ value of X70 steel pipeline was 23.4% lower than that in hydrogen-free environment. When the hydrogen pressure continued to increase to 0.96 MPa and 1.2 MPa, the fracture toughness J₀ value decreased by 35.3% and 37.1%, respectively. With the increase of hydrogen pressure, the fracture morphology changed from ductile fracture to ductile-brittle mixed fracture, and finally to brittle fracture.