The invention discloses a preparation method and application of a supported metal catalyst. The supported metal catalyst comprises carrier framework materials and nano particles, loaded on the surfaces of the carrier framework materials, of metal or metal oxide, or metal ions chelated on the surfaces of the carrier framework materials, wherein the metal ions and nano particles of the metal or metal oxide are loaded on the surfaces of the carrier framework materials through the polymerization layers, adhered to the surfaces of the carrier framework materials, of catechol derivatives. The preparation method of the supported metal catalyst has the advantages that the method is simple, various carrier framework materials are used, one or more metal ions or nano particles can be loaded, and universality is achieved; the supported metal catalyst is good in active metal dispersity, large in carrier specific surface area, low in use amount, low in cost, and the like; the catalyst loaded with noble metal is catalyst material which is widely used and environmental friendly and is efficiently applicable to environmental chemical engineering fields such as dye wastewater decoloring, wastewater organic pollutant removing, car tail gas treatment, air purification, hydrogenation and reforming catalytic reaction, gas sensors and fuel cells.