The invention discloses sugar-free throat lozenges and a preparation method thereof. Each 100g of the throat lozenges are mainly prepared from the following raw materials by weight: 20.9g-51.2g of isomalt, 10.00g-15.00g of isatis roots, 8.00g-16.00g of mesona, 8.00g-10.00g of rehmannia roots, 5.00g-9.00g of dried tangerine peel, 6.00g-8.00g of fructus momordicae, 4.00g-6.00g of chrysanthemum flowers, 3.00g-5.00g of raw dendrobium officinale, 1.00g-3.00g of honeysuckle flowers, 1.00g-3.00g of licorice roots, 1.00g-1.50g of platycodon roots, 0.25g-0.30g of ophiopogon roots, 0.80g-1.00g of lily roots, 0.50g-0.70g of prunella vulgaris, 0.15g-0.30g of natural menthol and 0.10g-0.30g of frangipani. The preparation method disclosed by the invention is simple and convenient, the obtained throat lozenges have an effect of clearing and benefiting the throat, are suitable for healthy people to use and also are suitable for people with diabetes and obesity; and the throat lozenges disclosed by theinvention have high stability and no hygroscopicity.