Abstract: The present invention relates to a visible-light-mediated one-step method for preparing phenol and cyclohexanone from cyclohexylbenzene (CHB). The method specifically comprises: under the irradiation of visible light, and with a hydrogen bromide solution as a catalyst and oxygen as an oxidizing agent, directly oxidizing cyclohexylbenzene in an organic solvent to break a carbon-carbon bond, so as to generate phenol and cyclohexanone. The method avoids such a process in a cyclohexylbenzene method in the prior art that cyclohexylbenzene needs to be first oxidized to obtain cyclohexylbenzene-1-hydroperoxide (1-CHBHP), then the mixture of the oxidation reaction products is treated, and then a cyclohexylbenzene peroxide is decomposed in an acidic condition to obtain phenol and cyclohexanone, and also avoids potential risks caused by the accumulation of peroxides.