This invention is related to a preparation method of a supported catalyst Mo—O—K-MexOy for the synthesis of methanethiol from H2S-containing syngas. The catalyst comprises of an active component of Mo—O—K-based species, an active promoter and a support denoted as metal (or metals)-carrier. The support is prepared by electroless plating method in such a way that the metal or metals chosen are plated onto the surface of the carrier. Transition metal, especially Fe, Co or Ni are selected to be the plating metal, while SiO2, Al2O3 or TiO2 are selected to be carrier. The catalyst thus prepared is found to be efficient for the synthesis of methanethiol from H2S-containing syngasor carbon oxides/hydrogen mixtures, especially regarding a minor formation of the by-product CO2.