The present invention provides a RNA virus-derived peptides with modified side chains, wherein the side chains of the RNA virus-derived peptide are modified by altering the side-chain length or charges thereof such that the RNA virus-derived peptide has a high binding affinity for viral RNA and an high cellular uptake capability. The present invention also provides a composition for inhibiting RNA virus wherein the RNA virus-derived peptide can effectively inhibit viral self-replication and treat related diseases by its high affinity for viral RNA. A drug delivery carrier is also provided, wherein the RNA virus-derived peptides can carry desired drugs to the intracellular target due to its cellular uptake capability and thereby enhances the drug-delivery and treating efficiency.