In order to study the effect of laser peening (LP) on the fatigue strength of TC17 titanium alloys, the alloys are processed by LP for two times, and the fatigue strength of the materials before and after LP are tested and compared with the lifting and lowering method. The results show that the 11.7 μm deep micropits form on the surface of TC17 titanium alloys after LP and the produced residual compressive stress is 2.46 times that before LP. The increase of the residual compressive stress leads to the location change of crack sources and the refinement of fatigue strips, and the fatigue strength of TC17 titanium alloys is increased by 3.9%.