Abstract: To study the influence of laser shock peening number and pulse energy on microstructure and surface hardness of TC17 titanium alloy, TC17 titanium alloy samples were laser shock peened with different process parameters. The results show that severe plastic deformation and a great deal of high-density dislocations, such as proliferate, pile up and tangle, are generated in the material surface layer in the process. The maximum depth of micro-pits created by single pulse can be 21.4μm. When pulse energy is 5J, and overlap impacts increase from 1 time to 4 times, the surface hardness of materials increases by 8.3%, 17.2%, 24.3% and 24.5% respectively, compared with parent metal. In the meantime, when overlap impact is 1 time, and pulse energy is 5J and 7J, the surface hardness increases by 8.3% and 14.2% respectively. The conclusion is that the surface hardness is enhanced with the increase of impacts and pulse energy. High density dislocation on material surface by laser shock processing is the key reason for the increase of surface hardness.