Transition-metal-catalysis is the main catalytic system for organic reactions, and supported metal catalysts are the key technique to realize heterogeneous transition-metal-catalysis. They anchor the active metal component on inorganic carriers, which retains the performance of transition-metal-catalysis to a certain extent while obtaining the advantages of easy separation and recycling. Among these catalysts, they can be classified into single-atom, cluster and nano catalysts depending on the dispersion of metal components, which can show discrepant catalytic properties due to the size distribution effect of metal components, thus adapting to organic reactions with different characteristics. Our group has devoted great efforts to the precise synthesis of uniform single-atom, cluster and nano catalysts on inorganic carriers and the development of strategies to optimize their catalytic performance.