A simple, eco-friendly, experimental and rapid synthesis of a new series of 2, 3-dihydroquinazoline-4(1H)-one derivatives were synthesized by the one-pot three-component reaction of isatoic anhydride, aromatic aldehyde and 4-chlorophenyl-1,3,4-thiadiazol-2-amine under microwave irradiation catalyzed by l-proline. Furthermore, The newly synthesized 2-phenyl substituted -1, 3, 4-thiadiazole-2-yl)-2,3-dihydroquinazoline-4(1H)-one derivatives were characterized by FT-IR, 1H-NMR, 13C-NMR and HRMS methods. All the synthesized compounds were tested for their in vitro antimicrobial, antifungal activity against bacterial and fungal strains. The remarkable features of this technique are easy procedure, high conversion and excellent yield with a short reaction time