Thiazoloquinazoline derivatives are a paramount important class of heterocycles that uses in drug research, as they have both of the property of thiazole and quinazoline which have shown anticancer activities.1 On the other hands, multicomponent reactions (MCRs) have been applied to produce complex molecules and medicinal compound, and have attracted much attention from synthetic organic chemists.2 Ionic liquids had been used as green catalysts because of its special chemical properties.3 In this investigation, a green protocol will be report for the synthesis of benzothiazolo-[2,3-b]-quinazolin-1-one derivatives via one-pot three-component reaction of arylaldehydes, 2-aminobenzothiazole and dimedone using magnetic ionic liquid as catalyst under solvent free conditions The reported method represents varied merits such as high yields, short reaction time and simple workup procedure.