This Paper, with the help of the device was made in this university as "rapid prototyping device base on direct metal laser melting", study interaction of metal powder apparent density and heat transfer experimentally. 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 dependence of thermal properties to metal powder apparent density. Changes in apparent density was established through the pressure applied to the raw powder bed. Because achieve to desirable apparent density through proper distribution is much expensive. This study was done in range of apparent density 44.75% to 56.4% compared to the density of pure iron. Comparing the samples produced in different densities it was understood that the pressure applied to the raw powder bed with the optimum point of arrest. In fact, the best quality of the manufactured parts, in density of about 46% was obtained.