The invention pertains to the field of food or medicine, and relates to a method for preparing modified starch, a liposome and a method for preparing liposome. Specifically, the method for preparing modified starch, comprises: (1) in a supercritical carbon dioxide medium, starch is used as raw material, ethanol is used as an entrainer, and the reaction is carried out under supercritical CO2 conditions to obtain a pretreated product; (2) separating and purifying the pretreated product of step (1); (3) using the pretreated product obtained in step (2) to prepare modified starch; and (4) separating and purifying the modified starch prepared in step (3). The liposome prepared from the modified starch of the present invention has good stability, encapsulation rate and bioavailability.