Green chemistry methods are important modern synthetic chemistry pathways with main advantages such as milder reaction conditions, shorter time, and higher yields. A series of quinazolinone based Schiff bases (1-27) have been successfully synthesized by using green synthetic methods, including microwave-assisted, ultrasound-assisted and mechanochemical synthesis, respectively. Desired compounds were prepared from 3-amino-2-methylquinazolin-4(3H)-one and substituted benzaldehydes with moderate to high yields (11-90%). Benzoxazinone and 3-amino-2- methylquinazolin-4(3H)-one, the precursors of Schiff bases, were prepared by microwave-induced synthesis. The structures of all Schiff bases are confirmed by 1H and ¹³C NMR spectroscopy and mass spectrometry as well. A novelty of this research is the application and comparison of green chemistry methods in the synthesis of desired compounds which are listed above. The simplicity of synthesis includes ethanol as a solvent and no need for further purification.