The phase transition of Ti-22 Al-27 Nb alloy induced by laser shock peening（LSP） was investigated

and the influence law of LSP parameters on the microstructure transformation was analyzed. The results indicate that the transition from B2 phase to O phase is increased with the increase of laser energy

laser overlapping ratio and impact times

and the surface microhardness as well as the depth of affected layer are also increased.The impact times have great effects on the transformation of O phase. When the impact times is increased from 3 to 7

the content of O phase near the surface is increased from 21.63% to 25.66% compared with the matrix. The LSP induces significant plastic deformation and introduces dislocation defects

leading to an increase in adiabatic temperature

which promotes the transition from B2 to O phase.