With a high-power and short-pulse Nd∶YAG laser, TC17 titanium alloys are processed by laser peening (LP), the isothermal oxidation weight gain experiment at the temperature of 400 ℃ is carried out, and the effect of LP on the isothermal oxidation performance of titanium alloys is analyzed. The study results show that, as for the TC17 titanium alloys after LP, if compared with those before LP, the isothermal oxidation weight gain at 400 ℃ decreases by 64.9%, and the oxide film on the material surface becomes more dense, which can resist the oxygen diffusion more effectively. The surface energy spectral analysis results show that the Cr on the surface of the oxidized sample after LP is more than that before LP. A large amount of Cr can improve the adhesive force between the oxide layer and the substrate, and thus LP can improve the isothermal oxidation resistance property of titanium alloys.