Abstract: Ti-15-3 alloy with various microstructures was obtained by quenching, furnace cooling and quenching+aging at 500℃ and 540℃, respectively, and then shot peened with the same process. The evolution with of microstructure, residual stress, hardness and surface roughness after shot peening was investigated. The results show that a large number of deformation twins were induced in the quenched alloy, stress-induced martensitic phase transformation was found in the furnace cooled alloy, and no big change of microstructure was produced in the aged alloy after shot peening. Surface residual compressive stress of the quenched alloy was the smallest after shot peening, and that of the furnace cooled alloy was the largest. Hardness of the quenched alloy was the lowest resulted in the greatest plastic deformation range and the largest roughness after shot peening. The furnace cooled alloy showed the highest surface hardness and relatively small plastic deformation range after shot peening. The alloy aged at 500℃ showed the highest hardness and after shot peening the surface roughness was the smallest. With increasing aging temperature to 540℃, the hardness and the plastic deformation range decreased.