Objective To understand the distribution characteristics and antimicrobial resistance trends of clinica-lly isolated bacterial strains from elderly patients in China, and provide scientific basis for the clinical treatment of infection in the elderly people. Methods Data of clinically isolated bacterial strains from elderly patients from China Antimicrobial Resistance Surveillance System (CARSS) in 2020-2024 were analyzed retrospectively. Antimicrobial susceptibility testing results were interpreted according to the guidelines of American Clinical and Laboratory Stan-dards Institute (CLSI) and the standards of American Food and Drug Administration (FDA). Statistical analysis was performed using WHONET 5.6 software. Results Among clinical isolates of elderly patients, the ratio of Gram-positive bacteria to Gram-negative bacteria remained stable at 1.0 ∶3.5. Gram-positive bacteria were mainly Staphylococcus aureus, Enterococcus faecium, Enterococcus faecalis, and Staphylococcus epidermidis. In 2023-2024, Staphylococcus hominis replaced Streptococcus haemolyticus as the fifth frequently isolated Gram-positive bacteria. The top five Gram-negative bacteria were Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Stenotrophomonas maltophilia. In 2024, Streptococcus agalactiae ranked among the top 20 clinical isolates of elderly patients for the first time (0.6%). Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase negative Staphylococcus (MRCNS) showed slightly decreased detection rates, and their resistance rates to most antimicrobial agents also decreased. However, resistance rate of MRCNS to linezolid slightly increased. The resistance rates of methicillin-sensitive Staphylococcus aureus (MSSA) to multiple agents decreased, but its resistance rate to levofloxacin increased from 12.9% to 14.3%. No Staphylococcus aureus was found to be resistant to vancomycin, linezolid, or teicoplanin. Among Enterococcus spp., Enterococcus faecalis showed decreased resistance rate to ampicillin, but increased resistance rates to linezolid; Enterococcus faecium exhibited decreased resistance rate to high concentration streptomycin, while its resistance rates to vancomycin and teicoplanin increased. The resistance rate of Streptococcus pneumoniae isolated from non-cerebrospinal fluid specimens to cefepime decreased from 10.1% to 6.1%. Among Gram-negative bacteria, the resistance rate of Escherichia coli to amikacin has increased to 5.0% in 2024. The resistance rate of Klebsiella pneumoniae to carbapenems remained at 12%, higher than other Enterobacterales. The resistance rates of carbapenem-resistant Klebsiella pneumoniae (CRKPN) to most antimicrobial agents were >60%. In 2024, the resistance rates of Pseudomonas aeruginosa to imipenem and meropenem decreased to 16.2% and 13.2%, respectively, while the resistance rates of Acinetobacter baumannii to carbapenems remained at 52.4%-57.9%. The resistance rate of Salmonella spp., to ceftriaxone has been increasing year by year from 15.9% in 2020 to 23.4% in 2024, and the resistance rates to levofloxacin, compound sulfamethoxazole, and chloramphenicol also presented upward trends. The resistance rates of Haemophilus influenzae to ampicillin, cephalosporins, and azithromycin increased, but the non-sensitivity rate to levofloxacin decreased. Conclusion From 2020 to 2024, antimicrobial resistance of clinically isolated bacteria from the elderly people showed a certain degree of fluctuation, with a slight decreased in the detection rate in MRSA. However, problems such as the increased detection rate of vancomycin-resistant Enterococcus faecium and the persistent high resistance of CRKPN still remain serious, indicating that persistent antimicrobial resistance surveillance and prevention in the elderly people should be strengthened.