Abstract: The magnetic flux leakage (MFL) characteristics of pipeline girth weld were analyzed using finite element method combined with the pull test based on axial magnetic flux leakage principle. By changing weld reinforcement and the size of ellipsoid defect in the center of weld, the magnetic flux density distribution curves were obtained. The results show that the magnetic field distribution of pipeline girth weld appears thickening-type characteristic when there is no defect in the weld center. The radial component peak-to-peak value and the axial component peak-to-valley value of magnetic flux density increase non-linearly. Magnetic flux leakage signals show the magnetic field distribution characteristics of the weld and the ellipsoid defect, that is, the superposition of the thickening by weld and the thinning by defect. Moreover, with the increase of weld reinforcements, the thinning type signal characteristics of the weld defect become weaker. The intensity of magnetic flux leakage signal for the same size defect follows the sequence as from strong to week:pipe wall, fusion zone and weld, indicating that the same defect is most likely to be detected in the weld center, which is consistent with the result of the pull test.