The present invention relates to the technical field of pharmaceuticals, and discloses an antibacterial application of a Dryopteris fragrans phloroglucinol compound flavaspidic acid BB. The present invention provides for the first time a method of chemical synthesis to obtain a flavaspidic acid BB compound, which has good antibacterial applications and effectively remedies shortcomings in the application of natural antibacterial compounds, and particularly provides an effective antibacterial solution for drug-resistant bacteria. Experimental results showed that the compound obtained by the present invention has strong antibacterial effects, especially exhibiting good curative effects against drug-resistant bacteria.