Abstract: OBJECTIVE To observe the effect of ceftazidime on inhibition of formation and clearance of Pseudomonas aeruginosa biofilm and analyze the mechanisms so as to provide guidance for clinical use of antibiotics. METHODS The 96 well plate crystal violet staining method was used to quantitatively analyze the effect of ceftazidime on inhibition and clearance of the P.aeruginosa biofilm, and the real-time PCR method was employed to perform the relative quantitative analysis of the expression of biofilm formation-related genes so as to observe the effect of ceftazidime on the formation of P.aeruginosa biofilm. RESULTS Ceftazidime had better effect on inhibition of growth of P.aeruginosa when the mature biofilms were not formed, however, ceftazidime could not effectively inhibit the growth of P.aeruginosa when the mature biofilms were formed.Ceftazidime was associated with the increased expression of the biofilm formation-related genes of P.aeruginosa. CONCLUSION Ceftazidime can promote the expression of the biofilm formation-related genes of P.aeruginosa.It is necessary for the hospital to avoid the use of ceftazidime for the treatment of the patients with chronic P.aeruginosa infection.