In order to research the inhibitory effect and mechanism of plant extracts on the biofilm of Pseudomonas luteola. The effects of 6 kinds of extracts， such as dandelion， honeysuckle， clove， cinnamon， mint and mulberry leaf， on the biofilm formation of Pseudomonas luteola were measured. The clearance rate and inhibition rate of biofilm were calculated. The results showed that the extracts of dandelion and honeysuckle， which contains the same functional components - chlorogenic acid (CA)， has the best inhibitory and scavenging effects on the biofilm of Pseudomonas luteola. Under the action of chlorogenic acid， the amount of biofilm was determined by crystal violet method， the metabolic activity of biofilm was determined by MTT method， and the apparent morphology of biofilm was analyzed by laser confocal scanning electron microscopy. CA had a significant inhibitory and scavenging effect on Pseudomonas luteola. The metabolic activity of biofilm was reduced under the action of CA. High concentrations of CA prevented the bacteria from conglutinating to form biofilm. The bacteria could form biofilm at low concentrations， but the stereoscopic property of the structure was low. Conclusion: CA from the plant extract could inhibit the formation of biofilm by inhibiting the growth of bacteria， weake the three-dimensional structure of mature biofilm， and have the ability to clear biofilm