The invention discloses a preparation method for an inorganic porous acoustic material. The preparation method comprises the following steps: successively importing 50-60 parts of calcium sulfate hydrate, 10-15 parts of modified starch, 10-15 parts of a retarder, 15-20 parts of paper pulp and 5-10 parts of water reducer into a stirring container, and importing 50-60 parts of water into the stirring container, adequately stirring, heating the mixed materials in the stirring container in 100 DEG C, stirring for half hour, continuously stirring until the mixed materials in the stirring container are dissolved and the mixed materials are sticky, finally putting the mixed materials in the stirring container in a storage tank for future use, and putting 15-20 parts of a foaming agent and 50-60 parts of the water into a foaming agent preparation tank and stirring. The preparation method for the inorganic porous acoustic material is capable of effectively guaranteeing the sound absorption performance of the whole acoustic material, effectively increasing the toughness of the whole acoustic material, providing the effective fireproofing, and providing a quiet sound-proof environment for a person affected by noise.