The invention relates to the field of adsorbents and particularly relates to a formula of an adsorbent in an iodotrifluoromethane gas switch cabinet and a preparation method thereof. The formula is prepared by mixing the following components according to certain proportions: a silica-gel drier, cyclodextrin, potassium iodide, water, ethanol, methanol, acetone, glycerin, ethylene glycol and calcium oxide. The adsorbent provided by the invention can be efficiently and widely applied to iodotrifluoromethane gas switch cabinet equipment, can adsorb the moisture, iodine and acid halide in the switch equipment at high adsorption efficiency, and can effectively delay corrosion of electrical elements such as buses, cables and solid insulators in the switch cabinet while preventing solid decomposition products such as iodine from being adhered to electrical elements and influencing the normal operation of the equipment.