Abstract:The color，microstructure，physical properties，and nutrient content of olive powder prepared by microwave，hot-air，vacuum，and vacuum-freeze drying methods were measured and analyzed to provide a theoretical basis for processing olive powder.Results showed that the color of the powder prepared by vacuumfreeze drying was better with higher brightness and lower red-greenness which is closest to color of fresh olives.The powders prepared by the hot-air and vacuum drying methods had lower oil absorption and higher hygroscopicity，with that prepared by hot-air drying having the highest bulk density and solubility.The powder prepared by vacuum-freeze drying had the lowest bulk density，lower water absorption，and high rehydration，fluidity，oil absorption，and solubility.The powder prepared by microwave drying had the highest water content and rehydration and had low water absorption，bulk density，oil absorption，and solubility. The powder prepared by microwave drying had reduced sugar and a lower loss of total acid content，whereas that prepared by hot-air drying had a lower loss of flavonoid content.The powder prepared by vacuum drying had a lower loss of total sugar and phenol content，whereas that prepared by vacuum-freeze drying had a lower loss of protein content.Regarding the microstructures of the prepared powders，those prepared by the microwave and vacuumfreeze drying methods had large inter-particle spaces，and the arrangements were smooth，complete，and less shrunk.The powders prepared by the hot-air and vacuum drying methods had small inter-particle spaces，and some of the powder samples were shrunken. Principal component analysis produced comprehensive scores for the olive powder samples in the following decreasing order：vacuum-freeze drying ＞vacuum drying ＞hot-air drying ＞microwave drying.