The invention discloses a diatomite water absorption pad and a preparation method therefor. The diatomite water absorption pad is prepared from the raw materials in parts by weight: 40-70 parts of diatomite, 10-25 parts of inorganic minerals, 1-5 parts of glass fibers, 15-50 parts of inorganic adhesive, 0.1-5 parts of organic adhesive, 0.1-1.0 part of setting retarder, 0.1-3 parts of auxiliaries and 20-60 parts of water. The preparation method comprises the steps: (1) uniformly stirring and mixing the diatomite, the inorganic minerals, the glass fibers, the inorganic adhesive, the organic adhesive, the setting retarder and the auxiliaries, then, adding water into the mixture, and carrying out uniform mixing, so as to obtain diatomite slurry; (2) pouring the diatomite slurry into a mold, then, shaking the mold on a shaking table, removing superfluous slurry, carrying out baking, and carrying out demolding, so as to obtain a crude product; and (3) sanding the crude product, thereby obtaining the diatomite water absorption pad. The diatomite water absorption pad can absorb water efficiently, can be used for removing harmful substances from air and adjusting air humidity, is environmentally friendly and is low in cost, thereby being suitable for being produced industrially.