Provided is a copper oxide catalyst for preparing isobutene by isobutane dehydrogenation, which takes nitrogen doped mesoporous carbon as a carrier and comprises 2-20% by mass of copper oxide as an active component, preferably 5-15%, being balanced with nitrogen doped mesoporous carbon. The preparation method comprises the following steps: mixing a copper-containing compound and citric acid at a mol ratio of 1:0.5-1:3; dissolving by adding water to prepare a blue solution with the copper concentration of 0.2-2.2 mol/L; adding nitrogen doped mesoporous carbon at a ratio of 319-3898 grams of nitrogen doped mesoporous per mol of copper into the aqueous solution; stirring at a constant temperature, drying, and roasting; and to obtain obtaining the copper oxide catalyst. The catalyst is used for preparing isobutene by isobutane dehydrogenation through oxidation by carbon dioxide, the conversion rate of isobutane can reach 25-70%, and the selectivity of isobutene can reach 70-96%. The catalyst free of noble metal and highly toxic chromium metallic oxide is low in cost, environment-friendly, easy to prepare, and suitable for industrial production.