The antioxidant capacity of aqueous extract of Se-enriched A. auricula（AESAA） in vitro was evaluated in this paper by measuring AESAA on DPPH free radicals, hydroxyl radicals, superoxide free radicals’ scavenging ability and reducing ability with the aqueous extract of A. auricula（AEAA） as a negative control and vitamin C（V_c） as a positive control. The results showed that: AESAA had stronger scavenging ability of DPPH free radicals, hydroxyl free radicals and superoxide free radicals and reducing ability than AEAA, but weaker than V_c. The antioxidant activity of AESAA was positively correlated with selenium content.