An interlocked covalent organic molecular cage with a trigonal-prismatic structure based on anthracene units and imine bonds was synthesized by a template-free and one-pot reaction in a relatively good yield. By comparing the single-crystal structures of the interlocked cage and two additional monomeric cages as reference compounds, a cause of weak supramolecular interaction-induced synthesis was proposed; π···π interactions induce the triphenylbenzene units as the core and anthracenes as side parts close to each other, which provides a possibility of the preorganization for the formation of the interlocked structure.