Abstract: To evaluate the biological activity of fermented bran, this experiment was conducted to assess the in vitro antioxidant activity of fermented bran aqueous extract by measuring the DPPH radical and hydroxyl radical scavenging activity and reducing power using FWBE raw material. The in vivo antioxidant effect of FWBE on zebrafish was evaluated by establishing an in vivo oxidative stress model induced by AAPH and measuring its ROS production rate, cell mortality and lipid peroxidation. In addition, a zebrafish cardiac injury model was established with terfenadine induction, and the effects of different concentrations of FWBE pre-exposure on the venous sinus-arterial bulb spacing (SV-BA spacing) and heart rate of terfenadine-induced zebrafish were determined to evaluate the protective effects of FWBE on zebrafish heart. In vitro antioxidant results showed that FWBE scavenged up to 79.40% (4 mg/mL) of DPPH radicals; 53.99% (4 mg/mL) of hydroxyl radicals; and 1.11 (4 mg/mL) of reducing power. In vivo antioxidant results showed that the rate of AAPH-induced ROS generation, cell mortality and lipid peroxidation were alleviated at optimal concentrations (P<0.05). FWBE pre-exposure significantly alleviated the terfenadine-induced reduction in heart rate and increase in SV-BA spacing in zebrafish (P<0.05), and its alleviating effect increased gradually with increasing FWBE concentration. In conclusion, FWBE has strong antioxidant activity in vitro and in vivo, and has the effect of alleviating cardiac injury.