The invention provides a method for preparing a porous hydrogen storage material. A solvent thermal synthesis method is adopted in the method, indium salt and organic carboxylic acid are used as reactants, piperazine is used as a template agent, the reaction temperature is controlled to be between 80 and 110 DEG C, the pH value of a reaction solution is regulated to be between 4 and 6, and then the porous hydrogen storage material is obtained; and the organic carboxylic acid is an aromatic ring of C6-C20 or a condensed ring with an aromatic ring. The metallic organic porous material prepared by the method not only has a good hydrogen storage effect at a low temperature, but also has a good hydrogen storage effect at the temperature slightly higher than room temperature. Proven by experiments, the hydrogen absorption quantity of the hydrogen storage material provided by the invention at the temperature of 100 DEG C under 20P reaches 30 cm<3>/g, and the hydrogen release quantity reaches32 cm<3>/g.