The 1-(2-naphthlmethyl) isatin-5-formamide compounds can inhibit SARS-3CL proteinase by binding to its substrate pocket, while the N-terminal octapeptide of SARS-3CL proteinase was found to act as a dimerization inhibitor. In this work, the dual functional inhibitors which can occupy both substrate pocket of SARS-3CL proteinase and its dimer interface were designed. Six title compounds were gotten by linking 1-(2-naphthlmethyl) isatin-5-formic acid and N-terminal octapeptides using a polyglycine linker through solid-phase peptide synthesis method. The in vitro inhibition activity against SARS-3CL proteinase was measured by continuous colorimetric assay using colorimetric substrate. Compound 3 showed the highest inhibition activity with an IC50(half maximal inhibitory concentration of a substance) of 3.8μmol·L-1. The change of inhibition activity with the linker length was studied. Inhibitors with the even spacers were showed better activity than the odd ones, which could be explained by the angle restriction of peptide bonds. The modulating of the aggregation state and enzyme activity towards SARS-3CL proteinase werestudied using sedimentation velocity experiments. Compound 3 was found to not only inhibit the enzyme activity of SARS-3CL proteinase, but also shift the monomer-dimer equilibrium of the enzyme. The integrated control result is inhibiting SARS-3CL proteinase dimer formation. This work provides an example of using synthesized compounds to study enzyme activity regulation mechanism.