The invention discloses a method for synthesizing (E)-2-benzylidene-1,2,3,5-tetrahydrobenzo[e][1,4]oxazepine by multiple steps, and belongs to the technical field of organic synthesis. The method comprises the following steps: 2-nitrobenzyl alcohol and propargyl bromide or propargyl alcohol are subjected to ether formation, and 1-nitro-2-(propynyloxymethyl)-benzene is obtained; then, reduction isperformed with iron powder / acetic acid or NiCl2(dppp) / tetrahydroxydiboron / organic base, and 2-(propynyloxymethyl)-aniline is obtained; 2-(propynyloxymethyl)-aniline is subjected to Sonogashira coupling with iodobenzene, and 2-[(3-phenyl-2-alkynyloxy)methyl]-aniline is obtained; amino is subjected to p-toluenesulfonyl protection, cuprous bromide / cesium carbonate ring closing is performed, deprotection is performed under the condition of metal sodium / naphthalene, and (E)-2-benzylidene-1,2,3,5-tetrahydrobenzo[e][1,4]oxazepine is obtained.