In order to investigate the effect of laser peening (LP) on surface biological corrosion resistance of medical Ti6Al4V alloy, LP experiment was carried out on Ti6Al4V alloy and the electrochemical corrosion property of the alloy was investigated using potentiodynamic polarization curve method. The surface morphology of etched samples was observed by scanning electron microscope, and the energy spectra were measured. The results show that the self-corrosion potential of LP samples shifts positively and corrosion tendency decreases in the range of tested parameters; the passivation current density decreases while the potential range of passivation region increases, and passivation performance is more stable; the breakdown potential shifts positively and pitting susceptibility also decreases; the corrosion current density and corrosion rate all decrease. Compared with the untreated samples, the self-corrosion potential of LP samples maximally shifts 0.209 V and the passivation current density is reduced by two orders of magnitude; the maximum increases of the potential range of passivation region and breakdown potential are 86.90% and 88.31%, respectively, and the self-corrosion current density is maximally decreased by 81.75%. Therefore, LP process can effectively improve the biological corrosion resistance of the medical Ti6Al4V alloy.