The effect of laser shock peening( LSP) on the surface integrity and four-point bending fatigue life of Ti6Al4V alloy was investigated. The surface integrity including residual stress,micro-hardness and micro-structure of LSP region was characterized by scanning electron microscopy( SEM),micro-hardness tester,X-ray diffraction( XRD)instrument and transmission electron microscope( TEM). The fatigue property was tested by MTS fatigue tester.And the fatigue fracture was observed with SEM. The enhancement mechanism of the LSP was also investigated. The results show that the predicted median value of the four-point bending fatigue life of the LSP specimens with the laser power density of 15. 9 GW/cm~2 is about 4. 2～23. 5 times larger than that of the non-treated specimens. The fatigue performance of the specimens increases with the increase of laser power density. The LSP shows higher fatigue life improvement than shock peening( SP). Besides,it is found that a residual compressive stress field with the depth of about 600～1 400 μm is formed after LSP. The micro-hardness of LSP region is increased by about 10% compared with un-treated region. And the density of dislocation in the LSP treated sub-surface layer is also larger than that of un-treated specimen.