NOVELTY - Preparing a catalyst having metal catalyst nanoparticles support on natural cellulose fibers comprises: treating natural cellulose fibers with an electron beam; heat-treating the electron beam-treated natural cellulose fibers; chemically treating the heat-treated natural cellulose fibers with an acidic solution to introduce an oxidizing group to a surface of the natural cellulose fibers to prepare a cellulose catalyst support; and supporting metal catalyst nanoparticles on the cellulose catalyst support by chemical vapor deposition or impregnation.    USE - The method is useful for preparing a catalyst having metal catalyst nanoparticles supported on natural cellulose fibers, including platinum catalyst nanoparticles for hydrogenation of tetralin or benzene, or oxidation of alcohol, nickel catalyst nanoparticles for desulfurization, denitrification, or demetallation, molybdenum catalyst nanoparticles for desulfurization, denitrification, or demetallation, and cobalt catalyst nanoparticles as co-catalyst for desulfurization, denitrification or demetallation and for platinum catalysts in fuel cells, and as a catalyst for Fisher-Tropsch reaction, oxidation and partial oxidation of hydrocarbons, reforming reactions, amination of ethanol, hydrogenation or water-gas shift reactions (all claimed).    ADVANTAGE - The method provides the catalyst having metal catalyst nanoparticles which are supported in a highly dispersed state on the natural cellulose fibers with a large surface area and uniform pore distribution, functional groups introduced to the surface of the natural cellulose fibers through specific pretreatment of the natural cellulose fibers, hence guaranteeing broad applicability to various catalytic reactions. In the method, the chemical vapor deposition effectively increases the amount of metal catalyst nanoparticles supported on the cellulose catalyst support without increasing the size of the metal catalyst nanoparticles or decreasing the degree of dispersion, even with increased reaction time.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a catalyst having metal catalyst nanoparticles supported on natural cellulose fibers, comprising: a cellulose catalyst support pretreated to allow metal catalyst nanoparticles to be supported on a surface of natural cellulose fibers; and the metal catalyst nanoparticles supported on the cellulose catalyst support by chemical vapor deposition or impregnation.