1,5-Benzoxazepine is an important active substance found in the development of new drugs. It has the properties of anticonvulsant, anti-tumor and improving cerebral ischemia. In this work, novel, efficient and green three-component domino reactions were developed, which used substituted o-aminophenol, β-cyclic diketones and active carbonyl compounds as raw materials, self-made magnetic nano-supported p-toluenesulfonic acid (CoFe₂O₄@SiO₂-PTSA) as catalyst, anhydrous ethanol as solvent, at room temperature. 37 fused 1,5-benzoxazepines with diverse structures were synthesized in one pot, and the mechanism of catalytic domino synthesis was proposed. This method abandons the traditional strong base dehalogenation hydrogen coupling method of aromatic halides, and has the advantages of novel synthesis method, mild reaction conditions, green reaction process, high efficiency, short time, and recyclable magnetic nanocatalyst, which provides a methodological reference for the effective synthesis of such compounds.