This paper presents an experimental study on interaction effects of apparent density and heat transfer charactristics of metal powder by Direct Metal Laser Sintering device which is developed at K. N. Toosi university of technology. Selective Laser Melting (SLM) is a direct fabrication of part through layer by layer powder deposition and successive laser beam irradiation. One of the important properties of the SLM is thermal conductivity and thermal diffusivity of the metal powder. In this paper, thermal conductivity and diffusivity of metal powder with various apparent densities were studied. According to the method of measuring (the difference between two temperatures), The tests showed the dependency of thermal properties to metal powder apparent density. Variations in apparent density was established through the pressure applied to the raw powder bed. This study was performed between apparent density of 44.75% to 56.4% compared to the density of pure iron. Comparing the samples which is produced in different densities, it is concluded that the pressure applied to the raw powder bed had an optimum point of arrest. In fact, the best quality of the manufactured parts, in density of about 46% was obtained.