Objective To understand the distribution of frequently isolated pathogenic bacteria from clinical specimens and their antimicrobial resistance changes in Hunan Province from 2012 to 2021, and to provide scientific evidence for the formulation and evaluation of antimicrobial clinical administration policies. Methods Species identification, selection of quality control strains and antimicrobial susceptibility testing agents were conducted according to the technical scheme of the China Antimicrobial Resistance Surveillance System (CARSS). Duplicate strains were excluded based on the principle of counting the first strain in each case. Statistical analysis was performed by WHONET 5.6 software. The the variations in constituent ratio and resistance rate of strains were analyzed with linear trend test, and the magnitude of change was described with Pearson correlation coefficient. Results From 2012 to 2021, the number of clinically isolated bacteria in the analysis increased from 82 759 to 312 914, with Gram-negative bacteria accounting for 69.5%-72.4%. The major Gram-positive bacteria were Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Enterococcus faecalis and Enterococcus faecium, and the major Gram-negative bacteria were Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii and Enterobacter cloacae. Isolation rate of Gram-positive bacteria increased yearly (r=0.022, P=0.001). Isolation rate of methicillin-resistant Staphylococcus aureus (MRSA) decreased from 34.3% to 24.8%. Isolation rates of vancomycin-resistant Enterococcus faecium and Enterococcus faecalis were less than 3% and 2%, respectively, presenting a downward trend. The detection rate of penicillin-resistant Streptococcus pneumoniae (PRSP) decreased from 5.6% to 1.0%. Except cefoperazone sulbactam, resistance rates of Escherichia coli to other tested antimicrobial agents showed decreasing trends (r < 0, P=0.001). Isolation rates of third-generation cephalosporin-resistant Escherichia coli (CTX/CRO-R-EC) and carbapenem-resistant Escherichia coli (CREC) decreased year by year (from 70.5% to 45.3%, and 12.2% to 2.0%, respectively). Resistance rates of Klebsiella pneumo-niae to imipenem and meropenem have increased year by year, reaching 9.1% and 11.0% respectively in 2021, while isolation rate of carbapenem-resistant Pseudomonas aeruginosa (CRPA) decreased from 28.5% to 15.0%. Resistance rates of Acinetobacter baumannii to most antimicrobial agents were 40%-60%, and remained relatively stable. Isolation rate of carbapenem-resistant Acinetobacter baumannii (CRAB) ranged from 39.5% to 59.6%. Conclusion The clinical isolation rates of most important special antimicrobial-resistant bacteria have been decreasing year by year, while the resistance rate of Klebsiella pneumoniae to carbapenem agents gradually increased. Antimicrobial stewardship as well as the prevention and control of healthcare-associated infection on specific antimicrobial-resistant bacteria should continue to be implemented in the future. The coverage and quality of antimicrobial resistance surveillance in Hunan Province should continue to be improved.