ObjectiveTo explore the effect of antimicrobial use density (AUD) on the detection rate of methicillinresistant Staphylococcus aureus (MRSA) and antimicrobial resistance rate of healthcareassociated Staphylococcus aureus (HASA) half a year later.MethodsFrom 2012 to 2015, all types of AUD, detection rate of MRSA, and antimicrobial resistance rate of HASA were calculated semiannually, correlation between antimicrobial resistance rate of HASA and all types of AUD in the same first half of year were analyzed with correlation analysis and multiple linear regression.ResultsFrom the first half of 2012 to the latter half of 2015, the total AUD declined from 128.2 to 49.0, except the AUD of carbapenems rose, AUD of other antimicrobial agents declined. From the latter half of 2012 to the latter half of 2015, 104 249 patients were admitted to the hospital, and 1 008 strains of SA were isolated from 40 884 specimens, 857 (85.02%) of which were communityassociated SA(CASA) and 151 (14.98%) were HASA. Isolation rate of HAMRSA declined from 31.25% in the latter half of 2012 to 12.50% in the latter half of 2015；isolation rate of CAMRSA rose from 7.08% to 16.08%, resistance rate of HASA was generally higher than that of CASA. Antimicrobial resistance rate of HASA to ciprofloxacin remained the same, to levofloxacin increased, to 8 other antimicrobial agents all declined; resistance rates of CASA to oxacillin, ciprofloxacin, clindamycin, gentamicin, and levofloxacin increased, but to other antimicrobial agents declined;  no SA strains was found to be resistant to vancomycin and linezolid. The resistance rate of HASA to azithromycin and erythrocin was correlated with the AUD of macrolides, resistance rate of HASA to clindamycin was correlated with the AUD of aminoglycosides, to gentamicin was correlated with the AUD of macrolides and the total AUD. ConclusionThe selective pressure of antimicrobial agents is still the important cause of the occurrence of antimicrobial resistance, decreasing the AUD of antimicrobial agents will help for reducing the detection rate of HAMRSA and drug resistance rate of HASA.