Under the terrible environment in the aero-engine, the blade, made of Ti-5Al-2Sn-2Zr-4Mo-4Cr titanium alloy, is prone to result in fatigue failure. So improving the titanium alloy performance is becoming very significant. In this paper, the microstructure and microhardness of Ti-5Al-2Sn-2Zr-4Mo-4Cr titanium alloy with and without laser shock peening (LSP) were examined and compared by XRD, TEM and microhardness test. The XRD tests pointed out that LSP generated the microstrains and grains refinement in the material surface. The TEM results indicated that great high density dislocations were generated and evolved into the dislocation wall, small-angle boundary and large-angle boundary. The nanocrystallites were formed and became more and more uniform after 4GW/cm2. The grains nanocrystallization in the surface layer helps to improve the material performance. The microhardness test result showed that LSP could increase the hardness by 20 percent or so. And the affected depth is about 700μm.