The invention discloses a perovskite type La2CuO4 nano material and a preparation method thereof. The preparation method comprises the following steps: adding lanthanum nitrate, copper nitrate and sodium dodecyl sulfate into deionized water, and carrying out ultrasonic dispersion for 10-30 minutes to obtain a solution a; adding sodium carbonate into deionized water, and carrying out ultrasonic dispersion for 10-30 minutes to obtain a solution b; under the condition of heating and stirring, alternately, slowly and uniformly dropwise adding the solution b and the solution a into a beaker filledwith a small amount of deionized water, controlling the pH value of the mixed solution to be 8.0-9.0, controlling the temperature of the mixed solution to be 60-80 DEG C, and keeping for 1-3 hours; aging the reactant solution at room temperature for 1-3 hours, washing and centrifuging a reaction product, and drying an obtained light blue precipitate; and calcining the dried precipitate in a tubular furnace to obtain the La2CuO4 nano material with the perovskite structure. The method disclosed by the invention is simple and is suitable for industrial production; and the obtained La2CuO4 nano material can be used for catalytic reforming hydrogen production of methanol water vapor, and a major breakthrough for producing hydrogen by utilizing methanol decomposition at a relatively low temperature is provided.