To increase the value and promoting consumption of purple yam, flour was prepared as a fast food with good flavor. The effects of main processing parameters， including ratio of solid to liquid, material flow and freeze temperature, on water content, solubility as well as anthocyanin content of yam flour during sprayfreeze drying were studied. By using the orthogonal experimental method with four factors and three levels, the optimal parameters for the sprayfreeze drying technology of yam flour was obtained. And the influences of sprayfreeze drying, spray drying, freeze drying and hot air drying on the physical, nutritional and antioxidant properties of purple yam flour were studied. The results indicated that the optimum process parameters for drying yam flour were determined as follows: ratio of solid to liquid of 1〖DK〗∶1, material flow of 25 mL/min and freeze temperature of -30 ℃. Under above conditions, the water content, solubility and anthocyanin content of purple yam flour were 3.89%, 23.12%,13.28 mg/100 g, respectively. Drying methods showed significant effects on the physical, nutritional and antioxidant properties of purple yam flours.