The present invention relates to a method for preparing an extract of the aerial part of Aster spathulifolius effective in preventing and treating hyperlipidemia and obesity and a composition comprising the extract. Since most of salt which is originally abundant in Aster spathulifolius, phenolic compounds which are unstable and susceptible to oxidation, and mucous substances are simply removed by the preparation method in accordance with the present invention, the present invention can significantly increase the content of terpenes, or the active ingredient, and reduce production cost. The composition of the present invention can be used as functional food for aiding the prevention and treatment of hyperlipidemia- and obesity-related arteriosclerosis, cardiovascular disease, cerebral thrombosis, liver disease, thrombosis, diabetes, etc.