In this study, the effects of different gas pressures on the shape and size of Al-12Si alloy powder produced by gas atomization method are investigated experimentally. Experiments were carried out at the Gas Atomization Unit, which was redesigned at Karabuk University Faculty of Technology Department of Manufacturing Engineering. Experiments were carried out at a stable temperature of 770 °C, at a nozzle diameter of 2 mm and by applying 6 different gas pressures (5-10-15-20-30-35 bar). Argon gas was used to atomize the melt. In order to determine the size and shape of Al12Si powders produced, scanning electron microscope (SEM) images and powder size analysis were performed by screen analysis method. As a result of the analysis, it was determined that the increase of the gas pressure caused the powder size to decrease and the powder shape to change from the ligament and the dripping structure to the spheroidal. It has been observed that the thinnest powders produced are in the gas pressure of 35 bar and the usually of the powders is complex