Molecular Dynamics simulation using Gromacs with OPLS-AA force field is performed for 100ns between SARS-CoV-2 main protease and Dexamethasone / Umifenovir drugs at 300 K/1 atm pressure. The trajectory of Root Mean Square Deviation (RMSD) and Radius of Gyration(Rg) emphasized the achievement of equilibrium and compactness. The drug-binding affinities on SARS-CoV-2 main protease are estimated via MM/PBSA method. The sign with magnitude of computed Gibbs free energy indicated the presence of strong interactions between SARS-CoV-2 and drugs of Dexamethasone / Umifenovir. The study revealed that the drug Dexamethasone is more effective over Umifenovir in binding SARS-CoV-2 main protease.