The invention discloses a preparation method of novel high-strength round particle potassium sulphate. A farm-oriented potassium sulphate powder is used without being pulverized, a pelleting auxiliaryaccounting for 2-5% of the total amount of the material is added and mixed evenly, the mixture enters agglomerating and pelleting equipment, proper amount of an acid is sprayed to regulate the pelleting, and the round particle potassium sulphate with the even particle size of 2-4 mm is obtained after drying, cooling and screening, the average strength of the round particle potassium sulphate is 28-45 N, the strength of the particle increases as the storage period prolongs, the nutrient content is high, the K2O content is 48.4-50%, the production process is simple and convenient, and the yieldis high. The chosen calcium oxide, magnesium oxide and calcium sulfate hemihydrate have the effect of binding pellets, and also provide the medium elements required for the plant. The particle potassium sulphate can be applied as an elemental potassium fertilizer, and also can be used as the raw material of a blended fertilizer.