This study described some essential viral and sera-characteristics of A/H7N9 virus infection in a 61-year old case patient. With the antiviral therapy and respiratory support, the patient showed a significant decrease of viral loads from 6.72 log10 copies/mL to 0 in 22 days, and a correlated increase of serum hemagglutination inhibition titers during the same period. Phylogenetic analysis demonstrated that the isolated strain was highly homologous to previous strains isolated in the southeast of China. Drug resistance-associated R292K mutation became detectable 17 days after antiviral therapy, but no remarkable influence on the viral clearance was observed.