The invention relates to starch-polyphenol composite nano-granules and a preparation process thereof. The preparation process comprises the steps that 1, a biological enzyme method is adopted to prepare debranched starch nano-granules: enzymolysis is conducted on gelatinized starch by using pullulanase to prepare a short amylase solution, ethyl alcohol titration is performed to prepare the starch nano-granules, and freeze-drying is performed to obtain starch nano-granule powder; 2, polyphenol adsorption and loading are performed to prepare the starch-polyphenol composite nano-granules: starch nano-granule turbid liquid is prepared, different amounts of polyphenol are added, the liquid is put in an oscillating water bath kettle, adsorption is performed at room temperature for different time, and ultra-filtration centrifugation, precipitate washing and vacuum freeze-drying are performed. The starch-polyphenol composite nano-granules are small in size, attachment forces of the nano-granules to tissues can be increased, the polyphenol delivery efficiency of the gastrointestinal tract is improved, the retention time of the polyphenol in the gastrointestinal tract is prolonged, and the bioavailability is improved. The starch-polyphenol composite nano-granules protect the polyphenol having bioactivity, prevent light in the outside environment, a pH value, oxygen and the like from affecting the polyphenol and improve the stability of the polyphenol.