This study investigated the serotypes and antimicrobial resistance profiles of prevalent Haemophilus parasuis strains on a large?scale pig farm in Guangdong Province. From 2024 to 2025，277 tissue samples（including heart，lung，joint fluid，and pericardial fluid）were collected from deceased pigs suspected of H. parasuis infection. Isolation，purification，serotyping，and antimicrobial susceptibility testing of H. parasuis were conducted. The results showed that 53 strains of H. parasuis were isolated and purified from the samples based on colony characteristics and PCR identification，yielding an isolation rate of 21.2%（53/277）. The predominant serotype was type 5，accounting for 73.58%（39/53），followed by type 1 at 11.32%（6/53）. Antimicrobial susceptibility testing indicated that the isolated strains exhibited relatively high sensitivity to several antimicrobial agents，including β?lactams（amoxicillin，penicillin sodium，cefotaxime，cefazolin，cephalexin，and compound amoxicillin［amoxicillin/clavulanate potassium］），the macrolide tilmicosin，the amphenicol florfenicol，the aminoglycoside neomycin，and the polypeptide colistin sulfate.The findings reveal a complex serotype distribution and severe antimicrobial resistance situation regarding H. parasuis on this farm. This study provides crucial data to support the prevention and control of H. parasuis disease on the farm.