Abstract: The proportions of hydrophilic groups were increased through an oxidation and grafting protein method on its surface for improving the performance of polystyrene as a kind of biofilm media, and some new hydrophilic groups and identifying point were introduced at the same time.The media surface energy was increased from 42 mJ·m^-2to 74.77 mJ·m^-2through oxidation, to 119.5 mJ·m^-2through grafting protein without oxidation and to 172.3 mJ·m^-2through grafting protein after oxidation respectively.The proportion of C—C bond on the corresponding surface of the media was decreased in the above three cases by 26.56%,18.64%,32.21% respectively.C—O bond was increased in the above three cases by 17.78%,16.35%, 25.56% respectively.The new hydrophilic groups were identified as —(C=O)—O—and —(C=O)—NHbonds.The result of the lab-scale test using synthetic wastewater showed that the amount and early adhesion rate of biofilm on the grafted protein media after surface modification increased evidently.