To investigate the effect of shot peening on surface or near-surface porosity defects of additively manufactured components, additively manufactured TC4 specimens were prepared by selective laser melting, and surfaces of the specimen were strengthened by shot peening, internal defects of the specimens were characterized before and after shot peening using computed tomography technology, three-dimensional visual reconstruction and analysis of the porosity defects were carried out, along with testing and analyzing microstructures of the specimens before and after shot peening. Microstructure, microhardness, and tensile properties of the specimens were tested and analyzed before and after strengthening. The results demonstrate that the porosity of the strengthened specimen was reduced by 0.32% compared with that of before, and the volume and spatial geometry of large pores were effectively altered. Post shot peening, the crosssectional hardness was increased by 23.38% and tensile strength was enhanced by 60.15%, indicating that shot peening can refine the grain structure and improve surface integrity and overall mechanical properties of the specimens.