The invention relates to a method for preparing an urchin-shaped hydroxyferric oxide and urchin-shaped ferric oxide nano material, which adopts a glucose guiding hydrolysis process and an annealing process and specifically comprises that: a ferrous salt is used as a raw material, the hydrolysis reaction is guided by adopting a saccharide structure indicator, the weight ratio of the glucose to an iron source is 0.5 to 5, and the molar concentration of the saccharide structure indicator is 0.02 to 0.2M; and then, an oxidizing gas is introduced into the raw materials at the temperature of between 25 and 100 DEG C, a yellow green urchin-shaped hydroxyferric oxide product is obtained through stirring reflux reaction, washing and filtration, and the product is annealed to form the urchin-shaped ferric oxide nano material with adjustable specific surface area and topography. The method has the advantages of simple operation, low requirement for equipment, low cost and high efficiency, and is easy in industrial application and popularization; and the synthesized nano material has the advantages of high purity, little impurity content and large specific surface area, can obviously improve the performance of a catalyst and a battery, and has remarkable economic benefit and social benefit.