Remdesivir is one representative nucleotide analog prodrug that has demonstrated therapeutic efficacy in the animal model of SARS-CoV-2 RdRp and effectively terminated viral RNA synthesis in the biochemical experiments through "delayed termination mechanism" . The chemical structure of Remdesivir's active form (RDV-TP) resembles that of natural adenosine triphosphate (ATP) (Fig. and). Previous studies have demonstrated that RDV-TP can efficiently compete with ATP incorporating into the nascent strand . However, three NTPs can still be consecutively added into the nascent strand after the incorporation of RDV-TP and the termination is delayed. This is because that the 1'-cyano group of Remdesivir could form steric and electrostatic interactions with the protein residues when it translocates from -3 to -4 site . In addition, biochemical experiments have further demonstrated that such termination can be overcome by increasing the concentration of the NTP pool and the full-length product containing Remdesivir in the RNA strand can be formed under biologically relevant condition .