The K24 nickel-based superalloy turbine blades of aero-engines often fractured at the root of tenon tooth, so laser shock peening (LSP) was suggested to treat the tenon tooth root to improve the fatigue strength. Because the treated region at tenon tooth root was very small and curved, ablating layer and confining layer were hard to paste on the surface. Therefore, the processing of micro-scale LSP without coating under water was suggested specially. In order to verify the feasibility for improving fatigue property of the turbine blade, K24 superalloy was treated by micro-scale LSP without absorbent coating under water in this work. The ablated surface under laser irradiation was observed by scanning electron microscope (SEM). Residual stress and micro-hardness were measured via X-ray diffraction stress analyzer and micro-hardness tester to obtain the influence rules of strengthening effect with different LSP impacts. A kind of simulated-blade was designed according to the work stress state of K24 superalloy turbine blade, and vibration fatigue tests were then conducted on the simulated-blades to investigate the effects in high-cycle fatigue performance. Experiment results indicate that more and more micro-holes are generated in laser irradiation region with LSP impact increased. The mechanically-polishing for the LSP treated surface are necessary post micro-scale LSP without coating to avoid micro-cracks generated before fatigue test. Compressive residual stress and micro-hardness are improved effectively in the material surface, but with a shallow affected layer, only about 100μm. Increasing LSP impact is an effective way to improve the affected layer depth. The fatigue strength of K24 superalloy simulated-blade is improved by 15.4% with five LSP impacts. The fatigue performance improvement is attributed to high-amplitude compressive residual stresses and cold-work hardening effect induced in material surface.