The HIV-1 Protease has been a critical drug target for war against AIDS and recently many protease inhibitors have been developed which inhibit the action of protease enzyme and prevent infection of HIV. However site-specific mutations occurring at one or more residues in HIV-1 protease has caused the development of resistance to protease inhibitors. In the present study, we have investigated the binding affinity of Darunavir to HIV-1 protease triple mutant (V32I, I47V and V82I) using bioinformatics approach. We have also highlighted the effect of mutations on the binding site residues and flap comprising residues in the HIV-1 protease by means of flexibility analysis. Molecular dockings were performed in order to gain insights into the binding mode of the Darunavir with HIV-1 protease structure. Subsequently, the docking results were also validated by means of PEARLS program. We hope that these results certainly will be helpful for the better understanding of mechanism of drug resistance.