Background Diabetes is characterized by a metabolic imbalance of blood sugar levels. α-amylase enzyme hydrolyzed starch into glucose units. Current therapy has significant side effects. Current investigation of in silico antidiabetic evaluation of phytoconstituents of Pterocarpus marsupium targeting α-amylase. Methods In silico studies were investigated to determine the binding affinity of phytoconstituents of Pterocarpus marsupium in additional with the crystal structure of α-amylase (PDB ID: 3BC9) with help of Pyrx in autodock vina software. Further, investigate the amino acid interaction residue and impacts on the inhibitory potential of the active phytoconstituents. Additionally, the pharmacokinetics and SwissADME and pkCSM were used as online servers for the toxic effects research. Further, studied the pocket region of amino acid for the binding of phytoconstituents using the Ramachandran plot. Result Molecular docking results proposed that pterostilbenes and liquirtigenin (-8.1 kcal/mol) had best docked against α-amylase as related to native ligand (-5.6 kcal/mol) and metformin (-5.3 kcal/mol). The active phytoconstituent has actively participated in interaction with the amino acid residue leads to blockage of α-amylase activity. Furthermore, the pharmacokinetic and In ADMET investigations, the phytoconstituents toxicological values are within allowable ranges. Conclusion The most promising outcome was revealed by the phytoconstituents of Pterocarpus marsupium that bind to α -amylase. However, it encourages the traditional practice of Pterocarpus marsupium and delivers vital information in drug development and clinical treatment. It promotes traditional approach of Pterocarpus marsupium and provides crucial knowledge for medical research and therapeutic care.