The invention discloses a method for preparing a hexagonal crystal type silicon phosphate adsorbent. The method comprises the following steps: adding an aqueous phosphoric acid solution to an aqueoussodium silicate solution at 20-30 DEG C at a rate of 50-100 ml/min while stirring at a stirring speed of 100-200 rpm to make the pH value be 3-4, and performing stirring for 10-20 min; carrying out areaction, raising the temperature to 50-60 DEG C, and keeping the temperature for 20-30 min; heating the obtained slurry to 115-125 DEG C, carrying out a reaction for 1-1.5 h, standing the treated slurry to normal temperature, filtering the treated slurry to obtain a filter cake, washing the filter cake with water, adding phosphoric acid to perform acid hydrolysis, keeping the molar ratio of phosphorus pentoxide to silica at 1.5-2.0 in the acid hydrolysis process, and carrying out spray drying; and calcining the dried material at 400-600 DEG C for 1-2 h, adding a silica sol binder, controllingthe addition amount of the silica sol to be 30-50% of the weight of the dried material, performing bonding for 30-40 min, and carrying out extrusion molding and drying to prepare the adsorbent. The hexagonal crystal type silicon phosphate adsorbent prepared by the method of the present invention has a specific surface area of 200-250 m<2>/g and a pore volume of 0.4-0.5 ml/g.