In this paper, the mechanical properties and microstructure of 7055 alloy subjected to static magnetic fields at different magnetic induction intensities (B = 0 T, 1 T, 3 T, 5 T and 7 T) were investigated. The dislocation characteristics, phase transitions, tissue textures, tensile properties, fracture morphologies and residual stresses were researched through advanced modern techniques. The results showed that the dislocation densities in the treated samples increased with increasing B, and a transformation of cellular dislocation to the low-energy network dislocation has been observed. In addition, the magnetic field has also played a role in grain refinement due to sub-grain’s formation and facilitating the common η (MgZn2) at grain boundaries to dissolve toward internal grains and transfer into η" phase, which contributes to the enhancement of the tensile strength and toughness of materials. At B = 3 T, the magnetic field weakened the lattice distortion and made a structural adjustment, and material performance arrived at the optimal elongation value 10.5%, residual stress 38 MPa and tensile strength value 555 MPa. Besides, the fracture morphologies were analyzed by Scanning Electronic Microscopy and the fracture characteristics were in agreement with the plasticity property.