The invention discloses a glass antidimmer and a preparation method thereof. The glass antidimmer is prepared from the following components: potassium chloride, magnesium sulfate, polyethylene glycol, lecithin, sodium carbonate, silicon dioxide, sodium ethylenediamine tetraacetate, glycidyl methacrylate, low-molecular alcohol and deionized water. The preparation method is as follows: the potassium chloride, the magnesium sulfate, the polyethylene glycol and the sodium carbonate are dissolved in the deionized water, so that a first blended solution is obtained; the lecithin, the silicon dioxide, the glycidyl methacrylate and the low-molecular alcohol are then stirred and blended, so that a second blended solution is obtained; the second blended solution is then heated, the first blended solution is added under a stirred state, stirring is continued after addition is complete, homogenization is carried out under normal temperature, and thereby the glass antidimmer is obtained. The glass antidimmer provided by the invention has good anti-mist property under high-temperature and low-temperature conditions, and the effect can last for a long time.