The virus SARS-CoV-2 has created a situation of global emergency all over the world from the last few months. We are witnessing a helpless situation due to COVID-19 as no vaccine or drug is effective against the disease. In the present study, we have tested the repurposing efficacy of some currently used combination drugs against COVID-19. We have tried to understand the mechanism of action of some repurposed drugs:Favipiravir (F), Hydroxychloroquine (H) and Oseltamivir (O). The ADME analysis have suggested strong inhibitory possibility of F, H, O combination towards receptor protein of 3CLpro of SARS-CoV-2 virus. The strong binding affinity, number of hydrogen bond interaction between inhibitor, receptor and lower inhibition constant computed from molecular docking validated the better complexation possibility of F + H + O:3CLprocombination. Various thermodynamical output from Molecular dynamics (MD) simulations like potential energy (Eg), temperature (T), density, pressure, SASA energy, interaction energies, Gibbs free energy (ΔGbind) etc., also favored the complexation between F + H + O and CoV-2 protease. Our in-silico results have recommended the strong candidature of combination drugs Favipiravir, Hydroxychloroquine and Oseltamivir as a potential lead inhibitor for targeting SARS-CoV-2 infections.