Abstract: This study aimed to explore the effects of pasteurization, ultra-high temperature instantaneous sterilization (UHT), and different spray-drying inlet temperatures on the powdered properties of foods for special medical purposes (FSMPs). The effects of different processing conditions on the reconstitutability and flowability of powdered samples were investigated by measuring wettability, dispersibility, solubility, angle of repose, Carr's index (CI), and Hausner ratio (HR). Influencing mechanism were determined through moisture content and activity, particle size morphology, and surface composition. When the spray drying inlet temperature was 150 ℃, compared with the pasteurized powders, the wetting time of the UHT powder samples was shortened by 45.7% (P<0.05), the water solubility index increased by 13.8% (P<0.05), and the dispersibility index decreased by 16.1% (P<0.05). When the spray drying inlet temperature was 170 ℃, the CI and HR of the UHT powder samples were 59.3% and 63.9% of those of the pasteurized powders, respectively (P<0.05), the moisture content was 81.4% of that of the pasteurized powders (P<0.05), and the average particle size was 1.94 times that of the pasteurized powders (P<0.05). The particles of the UHT group showed agglomeration under scanning electron microscopy. In addition, the surface composition analysis and laser confocal scanning microscopy showed that the surface lipid content of the UHT group reach up to 43.3%. With increasing spray drying inlet temperature, reconstitutability did not show a significant change (P>0.05), whereas flowability showed a significant increasing trend (P<0.05). In summary, different sterilization methods and spray-drying inlet temperatures have significant effects on the reconstitutability and flowability, moisture content, particle size morphology, and surface lipid content of FSMPs in powdered. This study reveals the effects and causes of different processing conditions on the powdered properties of FSMPs, thereby providing theoretical guidance for optimizing production processes and enhancing the commercial value of these products.