A novel synthetic strategy of cascade C−H activation/C−S coupling/C−O cyclization reaction by using metal organic framework material Cu3(BTC)2 as catalyst is investigated. In this method, Cu3(BTC)2 can effectively catalyze the hydroxylation of the ortho‐Csp2‐H of benzenethiol, and then the coupling reaction and intramolecular C−O coupling cyclization. Phenoxathiine derivatives are efficiently prepared by one‐pot method. In our work, a series of phenoxathiin derivatives were obtained in good yield by this method. At the same time, the reaction mechanism was explored through conditional control experiments.