This paper investigates the effects of porosity of the forming parts by laser cladding method. In the experiment,the laser cladding has been applied to build up the bulk clad on the thin layers formed by selective laser sintering,and the surface porosity with various laser powers has been characterized by imprint method. In the numerical analysis,a computation model was developed to analyze the porosity based on the surface tension and energy of cladding powders at various temperatures. The results show a good conformity between the numerical analysis and the experimental measurement.