Abstract: The effects of different excrement extracts of medical pteridophytes of the six species of Dryopteridaceae on the growth of a few kinds of common microorganism have been studied,the results have showed that they have a very good antibacterial effect generally,specially to Staphylococcus aureus.The greatest antibacterial ratio reached 90.4 percent;The antibacterial effects of the three genera of Dryopteridaceae have been compared,Polystichum is the most superior generally;In excrement extracts,alcohol extract is not superior to water extract obviously.