Objective:To understand the epidemiological and clinical characteristics of human infection with avian influenza A(H3N8) virus and the molecular biological characteristics of the pathogen, and provide scientific evidence for the prevention and control of human infection with avian influenza A(H3N8) virus.Methods:An epidemiological investigation was conducted for a case of human infection with avian influenza A(H3N8) virus in Changsha in May 2022 to collect the information about exposure history, route of infection, onset and treatment, potential contacts and other possible exposures for a descriptive analysis. Nucleic acid detection and gene sequencing were used to detect the pathogen and analyze the genetic characteristics.Results:The case had a history of exposure to live poultry trading market 6 days before the onset of illness. Subtypes H3 and N8 of avian influenza virus were detected in live poultry markets. Deep gene sequencing showed that the virus had adaptive mutations in mammals, reduced sensitivity to alkamine agent, and no resistance mutations related to neuraminidase inhibitors and polymerase inhibitors were detected.Conclusion:The case was infected due to exposure to the live poultry market environment contaminated by avian influenza A(H3N8) virus, and no human to human transmission was found.