Objective:To study the effects of baicalin and astragaloside IV on the formation of Pseudomonas aeruginosa biofilm. MethodsThe Pseudomonas aeruginosa PAO1 standard strains were selected,and baicalin and astragaloside IV were used to intervene culture of PAO1 biofilm in vitro,with azithromycin as the positive control and 0.9% NaCl solution as the negative control. The morphology of biofilm under different culture conditions was observed by confocal microscopy after FITC-ConA staining. Meanwhile,the total RNA was extracted by TRIzol and the expression of LasI mRNA was detected by RT-PCR. The content of glycocallyx(GXL)in PAO1 biofilm was determined.  Results:①For the comparison of the effects of intervening in biofilm TE (structure-entropy) and biofilm thickness and inhibiting GLX production and LasI mRNA expression of quorum-sensing(QS)system,there were significant differences between the normal saline group and baicalin or baicalin+astragaloside IV or azithromycin group(P<0.01),but there were no significant differences between the normal saline group and astragaloside IV group(P>0.05). ②For the comparison of the effects of intervening in biofilm TE (structure-entropy) and biofilm thickness and inhibiting LasI mRNA expression of QS system,there were no significant differences between the baicalin group and azithromycin group(P>0.05),but the effect of inhibiting GLX production in the baicalin group was weaker than that in the azithromycin group(P<0.05). For the comparison of the effects of intervening in biofilm TE (structure-entropy) and biofilm thickness and inhibiting GLX production and LasI mRNA expression of QS system,the effects in the baicalin+astragaloside IV group were weaker than those in the azithromycin group(P<0.05 or P<0.01). And there were no significant differences on these effects between the astragaloside IV group and azithromycin group(P>0.05).  Conclusion:Baicalin shows the obvious effects of intervening in Pseudomonas aeruginosa biofilm formation,reducing GLX production and inhibiting LasI mRNA expression,while astragaloside IV shows no obvious effects.