Objective To explore the distribution and drug resistance of pathogenic bacteria of infectious diseases in a grade-A tertiary hospital from 2020 to 2022.Methods The clinical data of totally 1 928 children with infectious diseases admitted to a grade-A tertiary hospital from 2020 to 2022 were retrospectively ana-lyzed.Bacterial identification and drug susceptibility tests were performed on sputum,blood,feces,secretions,urine and cerebrospinal fluid samples of all children after admission,and then the distribution of pathogenic bacteria and drug resistance were statistically analyzed.Results In this study,a total of 1 928 strains of non-repeating pathogens were isolated from a grade-A tertiary hospital from 2020 to 2022,and the pathogens were mainly isolated from the sputum(67.17％),followed by blood(12.03％),feces(11.00％),secretions(6.48％),urine(2.70％)and cerebrospinal fluid(0.62％).Among the 1 928 strains,1 202 gram-negative strains(62.34％)were mainly Haemophilus influenzae and Moraxella catarrhal,accounting for 24.17％and 15.82％respectively.There were 726 strains of gram-positive bacteria(37.66％),mainly streptococcus pneu-moniae and Staphylococcus aureus,accouting for 21.59％and 12.29％respectively.In addition,the pathogens in 2020-2022 accounted for 32.57％(628/1 928),38.43％(741/1 928)and 28.99％(559/1 928),respective-ly.The resistance rates of Haemophilus influenzae to ampicillin/sulbactam,cotrimoxazole,sulfamethoxazole/trimethoprim were more than 65.00％.The resistance rates of Moraxella catarrhal to cotrimoxazole,ampicil-lin/sulbactam were more than 40.00％.The resistance rates of Streptococcus pneumoniae to clindamycin,pen-icillin,sulfamethoxazole/trimethoprim and erythromycin were more than 87.00％.The resistance rates of Staphylococcus aureus to clindamycin,erythromycin and penicillin were more than 47.00％,and the resistance rate to penicillin was 88.61％.Conclusion From 2020 to 2022,the pathogens of infectious diseases in a grade-A tertiary hospital are mainly gram-negative bacteria,and there are different degrees of resistance to common-ly used clinical antibiotics.Therefore,in clinical practice,nosocomial infection prevention and control measures should be strictly implemented,antibiotics should be used carefully,and antibiotics could be selected reasona-bly according to the distribution characteristics of children's infection and drug sensitivity test results,which is of great significance for the prevention of hospital infectious diseases.