Abstract: OBJECTIVE To investigate the destructive effect of minimum inhibitory concentration (MIC) of baicalein on swimming motility, swarmming motility and twitching motility of Pseudomonas aeruginosa and provide basis for studying its effects on bacterial biofilm, so as to provide references for clinical medication. METHODS The experiments were divided into control group, different sub-MIC concentrations of baicalein group and clarithromycin group from Mar.2015 to Jul.2015. The MIC of test drugs were measured by the double dilution method. Different medium were made, germ-free toothpick was vaccinated by an overnight single strain in the tablet, the shape of the zone that bacteria was observed,and the zone of motilities were measured to assess the motility of bacteria. RESULTS The concentric region diameters formed by the swimming motility of P. aeruginosa in different concentrations of baicalein groups had no difference with control group, and the diameters of different concentrations of baicalein groups and control group were bigger than clarithromycin group (P<0.05). The surrounding of the circular area formed a sharp of radial-like gear in control group, but smooth surrounding could be seen in baicalein groups with the concentrations of 128μg/ml, 64μg/ml and clarithromycin group, without pseudopodial radiation. Their diameters of the circular area were smaller than those of control group (P<0.05). CONCLUSION It is shown that sub-MIC concentrations of baicalein cannot inhibit the swimming motility of P. aeruginosa, but can inhibit the swarming motility and twitching motility significantly. It is shown that baicalein with the concentration of 64μg/ml can inhibit the twitching motility of P. aeruginosa and have no difference with clarithromycin.