Antiviral agent 25 (compound 6g) is a new non-peptide analog covalent inhibitor of SARS-CoV-2 3CL pro. Antiviral agent 25 has a strong inhibitory effect on SARS-CoV-2 3CL pro and SARS-CoV-2 PL pro with IC 50 values of 0.118 µM, 0.448 µM, respectively. Antiviral agent 25 has antiviral effect on SARS-CoV-2 with an EC 50 value of 7.249 µM.