To investigate the change in  drugresistance of Pseudomonas aeruginosa (P. aeruginosa) to βlactam antibiotics in a hospital, so as to provide reference for treatment of P. aeruginosa infection.MethodsDrug sensitivity tests of 2 127 strains of P. aeruginosa isolated fom clinic between 1999—2007 to 18 kinds of antibiotics were analysed.ResultsResistance of P. aeruginosa to 18 kinds of βlactam antibiotics  increased year by year during  the past 9 years, there was significant difference between each year (P<0.05 or P<0.01). The total resistant rates to meropenem, imipenem and ceftazidime were below 30%. ConclusionP. aeruginosa was resistant to many kinds of βlactam antibiotics, and resistant rate increased year by year, in order to control and slow down the emergence of the resistant strains , the use of third generation cephalosporins and carbapenems should be properly controlled .