To evaluate the susceptibility of seasonal influenza viruses circulating in mainland of China to antiviral drugs,this study tested seasonal influenza viruses isolated during the 2023?2024 influenza season for resistance to neuraminidase inhibitors and Baloxavir. Of the 5,341 seasonal influenza strains analyzed using phenotypic methods,nine A(H1N1)pdm09 strains exhibited highly reduced susceptibility to Oseltamivir,all carrying the NA?H275Y amino acid substitution. Additionally,two B/Victoria lineage strains showed reduced susceptibility to both Oseltamivir and Zanamivir,with NA?I348T or NA?D197N substitutions,respectively. Of the 1,207 seasonal influenza viruses assessed through genotypic analysis,one A(H1N1)pdm09 strain had dual PA?K34R and PA?E198K substitutions,and two A(H3N2)strains carried a PA?L28P substitution,indicating potential reduced susceptibility to Baloxavir. Overall,the findings suggest that seasonal influenza viruses circulating in mainland of China during the 2023?2024 influenza season remain generally sensitive to neuraminidase inhibitors and Baloxavir,making these drugs suitable options for treating influenza infections. However,continued surveillance of antiviral susceptibility is essential.