Abstract: Akebia trifoliata var. australis seed protein isolate (API) was prepared using the methods of alkali extraction and acid precipitation. The physicochemical and functional properties of API were characterized. The results showed that API contained 17 kinds of amino acids. Glutamic acid and aspartic acid were the most abundant amino acids in API, consistent with most storage proteins. With respect to nutritional parameter, threonine was found as the first limiting amino acids for API. From the analysis of SDS-PAGE, molecular weights of API were from 25. 0 ~ 35. 0ku. Accounting for 31. 2% and 36. 6%. β-strand and random coil were found to be the major secondary structures in API. The isoelectric point of API was between 4 and 5. Protein solubility and the foaming capacity were minimal at that pH values.