Abstract: OBJECTIVE To investigate the current status and the changing trend of nosocomial infection (NI) and antimicrobial use in hospitalized patients of a tertiary class-A hospital, so as to provide a basis for formulating prevention and control measures of NI. METHODS Bedside visiting in combination with medical record review method was adopted to investigate the distribution of NI, antimicrobial use, and bacterial culture of all inpatients on survey day of 2014, 2016 and 2018. RESULTS The prevalence rate of NI was 3.28% in 2014, 2.99% in 2016, 2.54% in 2018, showing a gradual downward trend, and the difference was significant (χ²=4.467,P=0.035). The prevalence rate of NI in Intensive Care Unit was the highest in the three years. The lower respiratory tract was the main infected site for NI. Gram-negative bacteria were the main pathogens causing NI. Acinetobacter baumannii ranked first in the three surveys. The proportion of Klebsiella pneumoniae increased year by year.The utilization rate of antimicrobial agents decreased from 55.26% to 38.41%, which showed a downward trend (χ²=258.795,P<0.001). Patients were mainly treated with one antimicrobial agent. The utilization rate of one-drug therapy increased from 67.50% to 81.25% (χ²=100.379,P<0.001). Among patients receiving therapeutic use of antimicrobial agents, the etiological delivery rate varied from 59.58% to 70.50%. CONCLUSION Prevalence rate of NI showed a obvious decreasing trend in this hospital. Clinical use of antimicrobial agent is increasingly reasonable and standardized. The prevention and control of NI had achieved significant efficacy.