The paper aims to improve the serviceability of TC11 titanium alloy and provide experimental basis and technical support for the popularization and application of LSP technology in aeronautical component of titanium alloy. The surface of TC11 titanium alloy with lamellar structure is nanocrystallized by laser shock peening (LSP). The pulse energy is 6 J, the pulse width is 20 ns, the spot diameter is 3 mm, and the overlap ratio is 50%. The microstructure of TC11 titanium alloy before and after LSP are characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM). Compressive residual stresses in different depth were measured by x-ray stress analyzer. The microhardness of different depth is measured by microhardness tester. The mechanical properties are tested by tensile tester. Finally, the fracture morphology is photographed by SEM. The results show that gradient nanostructures are formed on the surface of TC11 titanium alloy after LSP, in which the grain size of the uppermost layer is about 10 nm, and the thickness of the deformation layer is about 200 μm. A large number of crystal substructure defects such as dislocation tangles, deformation twins and stacking faults are formed in the subsurface layer. The maximum compressive residual stress and microhardness exist in the surface layer of titanium alloy after LSP. The surface residual stress is about –267 MPa, the surface microhardness is about 425HV, and the corresponding values decrease gradually with the increase of the distance from the surface. In addition, the tensile strength and yield strength of TC11 titanium alloy after LSP are 1293 MPa and 1162 MPa respectively, which are 19.4% and 18.3% higher than those before LSP. But the elongation decreases slightly, about –8.9%. The fracture morphology changes from typical ductile fracture to quasi-cleavage and ductile mixed fracture. Under the combined action of gradient nano-structure and residual compressive stress after LSP, LSP-TC11 titanium alloy obtains good strength-plasticity matching.