Abstract: Chestnut shells, as a by-product of chestnut processing, were selected as raw materials. By contrast with unprocessed chestnut shells, three kinds of chestnut shells processed by different methods (boiling, roasting and frying) were tested on its major component contents and free radical scavenging activity. The results showed that unprocessed chestnut shells contained the highest water-soluble protein (40.58 mg/g) and proanthocyanidins (28.7 mg/g), which were reduced through processing. Flavonoid contents in unprocessed chestnut shells was 14.04 mg/g, while flavonoids were higher in the boiling, roasting and frying processed shells with 15.59, 22.00 and 28.58 mg/g, respectively. Roasted chestnut shells contained the highest levels of polyphenols (17.05 mg/g) and unprocessed chestnut shells contained the lowest level (9.21 mg/g). The polyphenols content was found to be significantly increased in the boiled and fried chestnut shells as compared to the unprocessed chestnut shells. Chestnut shell extracts were subjected to assess their scavenging capacity on DPPH free radicals and hydroxyl radicals. The obtained results revealed certain free radical scavenging capacity of the chestnut shell extract, and unprocessed chestnut shell extracts showed lower antioxidant activity on DPPH free radicals and hydroxyl radicals than the other extracts, with 55.69% and 43.19%, respectively.