The invention discloses a preparation method of a porous sheet-structure AZO adsorbent. The preparation method comprises the following steps: dissolving aluminum nitrate nonahydrate into a zinc salt aqueous solution; then adding the mixture into a hexamethylene-tetramine (HMTA) aqueous solution; uniformly mixing, and then performing hydro-thermal reaction; and putting a precursor obtained after the reaction into a muffle furnace for calcination, thereby obtaining porous sheet AZO powder. According to the method, the specific area of the adsorbent is increased by calcining and the electric property of the surface of the adsorbent is changed by doping aluminum ions, so that the adsorptive capacity of the adsorbent to dyes is enhanced. The porous sheet-structure AZO adsorbent prepared by the method disclosed by the invention has the advantages of simple preparation process, stable performance, high adsorbing efficiency, innocuity and the like, can be used for removing organic pollutants, and can be used in the field of photocatalysis.