Objective To understand the current situation and dynamic changing trends of healthcare-associated infection (HAI) in a tertiary first-class hospital in the northwest of Hunan Province from 2015 to 2024, and provide scientific basis for optimizing infection control strategies. Methods A single-day cross-sectional survey method was employed to investigate the HAI prevalence rates of hospitalized patients on the given survey day each year from 2015 to 2024. The standardized survey protocol on prevalence rate issued by the National Medical Institution Infection Surveillance Network was strictly adhered, lanqingting real-time HAI monitoring management platform was adopted to retrieve cases from the hospital information system, and R4.2.2 was applied for statistical analysis. Results From 2015 to 2024, the prevalence rate of HAI decreased from 3.03% in 2015 to 1.76% in 2024 (Z=-3.37, P<0.001), and the HAI case prevalence rate decreased from 3.55% in 2015 to 2.20% in 2024 (Z=-2.81, P=0.005). Department of critical care medicine continuously had the highest HAI case prevalence rate, which presented a downward trend over time (Z=-2.84, P=0.004). The main site of HAI was lower respiratory tract, accounting for 39.36% to 48.15%, bloodstream infection increased from 3.57% in 2015-2016 to 10.60% in 2023-2024 (Z=2.41, P=0.016). A total of 302 strains of HAI pathogens were detected, including 212 strains (70.20%) of Gram-negative bacteria, mainly Pseudomonas aeruginosa (n=55, 18.21%), Escherichia coli (n=45, 14.90%), Acinetobacter baumannii (n=33, 10.93%), and Klebsiella pneumoniae (n=31, 10.26%). 65 strains (21.52%) of Gram-positive bacteria were identified, with Enterococcus faecium (n=19, 6.29%) and Staphylococcus aureus (n=18, 5.96%) accounting for the highest proportions. 25 fungal strains (8.28%) were detected, mainly Candida albicans (n=11, 3.64%). The use rate of antimicrobial agents showed a downward trend over the past decade (Z=-4.01, P<0.001). Therapeutic antimicrobial use accounting for 82.42%, and its proportion increased over time (Z=6.02, P<0.001). Prophylacticantimicrobial use accounted for 16.42%, showing a decreasing trend (Z=-2.75, P<0.001). The pathogen detection rate presented an upward trend over the past decade (Z=13.01, P<0.001). Conclusion The prevalence rate and case prevalence rate of HAI present a downward trend in this hospital. In the future, it is necessary to establish a monitoring data-based dynamic analysis mechanism, achieve timely feedback and intervention in data monitoring, pay attention to high-risk links in department of critical care medicine, implement precise prevention and control mearsures, perform targeted prevention and control for lower respiratory tract, urinary tract, and bloodstream infection, optimize diagnosis and treatment processes, use antimicrobial agents rationally, and pay attention to the prevalence trend of Gram-negative bacteria.