In order to study the effect of laser shock processing (LSP) on the electrochemical corrosion resistance of magnesium alloys, the electrochemical corrosion behaviors in 3.5% (mass fraction) NaCl solution of AZ31, AZ61 and AZ91 magnesium alloys are investigated by electrochemical method and Ndglass laser with the wavelength of 1064 nm and pulse width of 20 ns. Its surface morphologies, microstructures, microhardness, self-corrosion potential and electrochemical impedance spectroscopy (EIS) are also examined and analyzed. The experimental results show that electrochemical corrosion resistance of magnesium alloys are improved after LSP. With the increasing of laser power density, the self-corrosion potential of magnesium alloy begins to move towards a positive direction, the corrosion current density decreases and the impedance arc becomes larger. When power density reaches to 0.7 GW/cm2, the current density increases and impedance arc becomes smaller. The effect of the Al content, solution and aging treatment on the corrosion potential and EIS of magnesium alloys by LSP are discussed and analyzed.