The aim of present work is to investigate the effect of cooling rate on hardness property of 1040 steel. The samples were prepared and heat-treated at 723 ºC and750 ºC subsequently were cooled by (Air, Water, and Furnace) three different methods. For this purpose, the hardness of the steel after heat treatment was examined by Vickers hardness test. The objective of this work is heating the material to obtaining desired properties of steel such as improving the toughness, ductility or removing the residual stresses, etc.