To study the effect of laser peening on microstructures and properties of TiAl alloy, TiAl alloy samples were treated by a Nd: YAG laser system with a wavelength of 1064 nm, a pulse-width of 20 ns, and a pulse-energy of range 0-22 J. The surface micro-hardness, roughness, and microstructural characteristics of the samples before and after laser peening were tested with a micro-hardness tester, a roughness tester and a Scanning Electron Microscope (SEM). The residual stress and pole figures of TiAl alloy were tested with X-ray Diffraction (XRD) and their high-temperature stabilities were analyzed. The experimental results show that the surface micro-hardness increases up to 33.4%, the roughness increases from 0.042 μm to 0.285 μm, the compress residual stress increases from 20 MPa to 297 MPa with the pulse energy up to 9 J, and the local textures and typical lamellar microstructures are generated. When the samples are heated for 4 h at 650°C, the residual stress value and micro hardness values have droped from 297 MPa to 230 MPa, and 377 HV0.2 to 345 HV0.2 respectively, and the (002) poles shift back to the center slightly. It concludes that the laser peening improves microstructures and properties of TiAl alloy significantly.