Abstract: To systematically reveal the influence of rotating speed on the particle size distribution structure and powder properties of IN625 alloy powder prepared by plasma rotating electrode process (PREP), five rotating speed levels ranging from 18000 to 28000 r·min?1 were set for PREP experiments. The results indicate that as the rotating speed increases, the particle size distribution undergoes a structural transformation: the proportion of fine powder (-270 mesh) increases from less than 15% to over 60%，while the span of particle size distribution of the powder gradually narrows. The dominant role of ligament disintegration (LD) mode in the atomization process is significantly enhanced with increasing rotating speed, and the more sufficient ligament disintegration directly promotes powder refinement. The powder sphericity remains above 0.96 throughout, but the defect type changes from elongated irregular particles caused by insufficient ligament disintegration at low rotating speeds to satellite particles formed by collision and adhesion of fine and medium particles at high rotating speeds. As the rotating speed increases, the oxygen and nitrogen contents of the as-produced IN625 powder increase slightly, while the flowability and apparent density decrease modestly, which is partially related to the increased proportion of fine powder (?270 mesh). This study identifies suitable rotating speed windows for different particle size requirements: rotating speeds of 24000 r·min?1 and above can achieve a relatively high proportion of fine powder, while the range of 18000 to 22000 r·min?1 is favorable for obtaining as-produced powder with excellent flowability and apparent density.