The effect of laser shock processing (LSP) on electrochemical corrosion behavior of 7075 aluminum alloy plasma arc weldments has been studied by using polarization curves, electrochemical impedance spectroscopy, residual stress tested by X- ray diffraction technique and scanning electron microscope (SEM) morphology of corrosion surface. The results show that the surface residual stress of weldments with LSP has been changed from tensile to compression, which leads to the improvement of the free-corrosion potential and pitting potential. The free-corrosion potential of weldments with 4 times LSP impacts is about 700 mV higher than that without LSP, and the pitting potential also occurs in about 1000 mV, besides the polarization curves exhibit an anode passivation zone in a wide range of potential with 712.9 mV. After grains being refined by LSP, the number of the microscopic holes and the volume of cavitation have been reduced, and the compactness of its surface microstructure has been improved. The infiltration of atoms such as Cl- in the NaCl solution has been effectively prevented, thereby the corrosion rate can be reduced, and the corrosion current density has been decreased by one orders of magnitude. The grains have been well-distributed along the β -phase in weldments with LSP. The activity of micro-galvanic made up of β phase and α base phase has been reduced, and the impact of passive resistance is nearly 30 times higher than that without LSP. Concentration polarization has been greatly improved.