Abstract The recrystallization processes of TiB2/6351Al and 6351Al deformation layers introduced by shot peening were investigated. The domain size and microstrain during annealing were calculated utilizing X-ray diffraction line profile analysis. The domain growth activation energy and microstrain relaxation activation energy were obtained by computer regression analysis. The results show that the recrystallization activation energy of both materials is larger than that of aluminum self-diffusion activation energy. And the recrystallization activation energy of composite is slight larger than that of alloy. Reinforcements have two effects on recrystallization process. Firstly, they will promote recrystallization of matrix at the early stage of annealing. Furthermore, they will impede the movement of grain and subgrain boundaries during annealing. The combination of the two opposite effects together with the lower volume of reinforcements and their inevitable inhomogeneous distribution weaken the influence of reinforcements on recrystallization activation energy.