The invention relates to a catalyst of three-dimensional ordered macroporous cerium-based oxide supported gold for purifying diesel soot and a preparation method thereof. The invention firstly provides an oxidation catalyst for the combustion soot particulate matter emitted by diesel vehicles. The oxidation catalyst is obtained by using a simple metallic oxide or a compound metallic oxide containing one or more rare earth metallic elements and having a three-dimensional ordered macroporous structure as the active component of a carrier supported precious metal, wherein the compound metallic oxide is a Ce-based solid solution-type compound metallic oxide, and the active component of the precious metal is the gold, and moreover, the average pore size of macropores in the carrier is 50nm-1mum. Adopting the catalyst of the carrier supported precious metal with the three-dimensional ordered macroporous structure is beneficial to the diffusion of the soot particulate matter in pore canals,improves the use ratio of the active superficial area of the catalyst and greatly reduces the combustion temperature of the soot particulate matter. The invention also provides a preparation method for the catalyst.