Abstract: OBJECTIVE To understand the current status of nosocomial infections in hospitalized patients of a tertiary three-A hospital, grasp the trend of nosocomial infections and find out the problems in prevention and control of nosocomial infections so as to provide scientific basis for further perfecting plans and measures for control of nosocomial infections.METHODS By means of cross-sectional survey, a survey of prevalence rates of nosocomial infections was conducted for the hospitalized patients of Shengjing Hospital of China Medical University at 0:00～24:00 on a day in the first ten-day period of December for 9 consecutive years, and statistical analysis was performed by using SPSS 25.0 software.RESULTS The prevalence rates ranged between 1.23% and 2.58% in 2012-2020, showing downward trend（tendency χ²=14.396,P＜0.001）. Respiratory tract, bloodstream and organ cavity were the most common infection sites, and there was significant difference in the distribution of infection sites（H=156.220,P＜0.001）. The submission rate of specimens ranged between 40.16% and 76.00%, showing upward trends（tendency χ²=20.538,P＜0.001）. The isolation rates ranged between 60.92% and 84.31%, showing downward trends（tendency χ²=7.944,P=0.005）. The gram-negative bacteria were dominant among the isolated bacteria, Acinetobacter baumannii was common. There was significant difference in the distribution of risk factors for nosocomial infections（H=198.776,P＜0.001）; hypoimmunity, long bedridden time and chronic disease were the most common risk factors.CONCLUSION The prevalence rates of nosocomial infections show downward trends in a tertiary three-A hospital. It is necessary to focus on the weak links, raise the submission rate of etiological examination and positive rate of test and pay attention to the risk factors so as to further ensure the medical safety.