Alkaline process was used to extract the starch from Dioscorea alata L., and the composition, transparency, freeze-thaw stability, settling property, water holding capacity, solubility, swelling, gelatinization and viscosity characteristics of the extracted starch were analyzed. The results showed that the content of amylose in legume Dioscorea alata L. was 27.05%. Compared with the starch from wheat, mung bean, and potato, the transparency, settling ability, water retention, and thermal stability of legume potatoes were found best. However, the freeze-thaw stability was poor, and it was difficult to gelatinize. The dissolving power and swelling power of the starch from legume potato increased with temperature, showing stronger interaction with water.