The invention discloses a technique for removing gallic acid in wastewater by using Aspergillus oryzae thallus, relating to the field of bioengineering. The technique comprises the following steps: by using Aspergillus oryzae as the initial strain, carrying out liquid shake culture and liquid thallus amplification culture to obtain the Aspergillus oryzae thallus; and removing the gallic acid in the wastewater by using the thallus. By using the technique, the removal rate of the gallic acid can reach 70-100%.