Abstract: The effects of magnetic field on the anodic dissolution rate and pitting corrosion of X70 pipeline steel with and without pre-charged hydrogen in 0.03 mol/L NaHCO₃+0.000 1 mol/L NaCl solution were studied by electrochemical test and surface morphology observation. The results show that in test solution, the open circuit potential of the non-hydrogen charged X70 (non-H) sample was in the active dissolution zone of the potential-pH diagram. The open circuit potential of the hydrogen charged X70 (H-X70) sample was about 20 mV more negative than that of non-H sample. After imposing a 0.4 T magnetic field, the peak current density significantly increased, and there was a significant positive shift in the transition potential of the sudden drop after the peak current density, delaying the transition to the stable passive state. When potentiostatically polarized in the active dissolution zone, a 0.4 T magnetic field increased the current density of both the H-X70 electrode and non-H electrode, resulting in obvious pitting corrosion on the surface and local accelerated dissolution on both sides in the horizontal direction of the polarized H-X70 electrode. Applying a magnetic field during potentiostatic polarization in the passivation zone generally increased the current density of H-X70 electrode.