ObjectiveTo investigate the changing trends in 4 continuous point prevalence surveys of healthcareassociated infection(HAI) in a hospital. MethodsThe occurrence of HAI  among all  hospitalized patients were investigated on a given day from 0:00 to 24:00 in May, 2006,2008, 2010, and 2012 respectively.ResultsA total of 4 497 patients should be investigated, 4 387 (97.55%) patients were actually investigated; 184 patients developed 209 times of HAI, point prevalence rate of HAI was 4.19%, case  prevalence rate was 4.76%. Trend χ2 test showed that HAI prevalence rate decreased gradually from 5.56% in 2006 to 2.76% in 2012（χ2=14.07，P＜0.001）.The main infection site was lower respiratory tract (55.03%),followed by urinary tract（14.83%）and upper respiratory tract（9.57%）.The overall usage rate of antimicrobial agents was 38.50%. Trend χ2 test showed that usage rate of antimicrobial agents decreased gradually from 2006 to 2012（χ2=5.13，P=0.023）；pathogenic detection rate in patients receiving therapeutic and  therapeutic plus prophylactic antimicrobial use increased gradually（χ2=40.81，P＜0.001）；single use of antimicrobial agents increased gradually（χ2=23.86，P＜0.001）. The rate of arteriovenous intubation , urinary catheterization , respirator use, and venous intubation in patients with HAI was significantly higher than those without HAI (27.17% vs 9.80%, 35.33%  vs 11.54%,13.59% vs  4.33% , 84.78% vs 63.24% respectively ,all P＜0.001）.  ConclusionManagement of rational use of antimicrobial agents has been achieved remarkably, control of HAI improved continuously; but control of invasive procedureassociated infection  need to be intensified, management of rational use of antimicrobial agents should  be paid  much attention.