Abstract Cacumen platyclade extracts were utilized as the reducing agent to prepare Au/Al 2 O 3 composites. XRD, BET, SEM, TEM were employed to characterize the properties of the catalyst. The catalytic activity of Au/Al 2 O 3 was studied by using NaBH 4 as the reducing agent and nitrophenol as the pollutant. The results showed that the Au/Al 2 O 3 catalyst, calcinated at 400 °C, exhibited the highest catalytic activity. With a catalyst dosage of 1 g L −1 , 2 mL NaBH 4 of 0.15 mol L −1 could degrade 96.5 % nitrophenol in 21 min at 298 K, with a reaction constant of 0.16 min −1 . Furthermore, the p -nitrophenol degradation ratio decreased by 0.8 % after ten cycles.