The invention provides an iron-based perovskite oxide catalyst for use in purification of carbon smoke particles emitted from diesel vehicles and a preparation method thereof. The catalyst is a three-dimensional ordered porous-mesoporous iron-based perovskite oxide consisting of more than two elements from rear earth metals, transitional metals, alkali metal and/or alkaline earth metals as activecomponents, wherein the pores of the oxide are formed into a uniform and ordered verse opal structure; and the mesopores are formed into a worm-like structure. In the invention, a carbon temperature supporting process is adopted, carboxyl-modified microspheres are used as pore temperatures, a surfactant is a mesoporous template, a firm carbon template can be formed by roasting in an inert gas, the supporting porous-mesoprous structure is free from collapse, and when roasted in the air, a perovskite structure can be formed. The catalyst of the invention can contact with carbon smoke particles effectively and is favorable for the conversion of small particles and gas molecules. Under a condition that the catalyst is in loose contact with the carbon smoke particles, the minimum combustion peak temperature is 396 DEG C, and the activity of the catalyst is equivalent to that of a noble metal catalyst.