Abstract: The effects of einnamic acid, phillyrin, emodin and sulfite andrographolide on bacterial biofilm （BBF） formation were studied by BBF model of Escherichia coli and Staphylococcus aureus. When bacteria formed into BBF at 37 ℃ after 24 hours, samples were added and then cultured for 24 hours. The absorbanee was measured to examine the impact of monomers on BBF after crystal violet staining. Results showed that the inhibition rates of emodin, phillyrin, cinnamic acid and sulfite andrographolide against BBF of Staphylococcus aureus under the concentration of 1.000 mg/mL were 67.26%, 10.91%, 18.26% and 17.05%, respectively, and the inhibition rates against BBF of Escherichia coli were 32.99%, 36.13%, 49.79% and 17.05%, respectively. Emodin had stronger inhibition to BBF of Staphylococcus aureus, while cinnamic acid had stronger inhibition to BBF of Escherichia coll.