A new method for generating nanoscale polycrystalline materials for molecular dynamics (MD) simulation analysis was proposed using pure iron. MD relaxation calculation was first performed on a cluster of single crystals, consisting of ninety atoms and having random orientation, and then the nanoscale polycrystal was obtained. In order to confirm the validity of the polycrystal generated, thermodynamic properties such as coefficient of thermal expansion and specific density were examined in the temperature range from 100 K to 3000 K. The results obtained showed fairly good agreement with those reported by other investigators.