The invention relates to a preparation method of a transition metal oxide / carbon-based laminated composite material. According to the preparation method, a conducting material such as metal carbide, metal nitride or metal carbonitride with a two-dimensional laminated structure is taken as a precursor, a gas containing oxygen elements is taken as an oxidant, and the two-dimensional conducting material is converted into the transition metal oxide / carbon-based laminated composite material by in-situ oxidation under the condition of controlling the oxidation temperature at 300-1000 DEG C and controlling the oxidation time at 1-300 min. The method disclosed by the invention has the advantages of simplicity and easiness in operation, controllable structure and morphology, controllable crystal form and electrochemical properties of metal oxides, and the like; the preparation method is environment-friendly, and nuisanceless, has no by-product, can be used for reducing the economic costs of traditional preparation methods, and can be popularized; and the transition metal oxide / carbon-based laminated composite material not only can be used as a key electrode material of a new energy storage device, but also can be used as a denitration catalyst, so that the material can be applied to the fields of environmental remediation, and the like.