The invention discloses a preparing method for high-purity manganese sulfate. The preparing method includes the steps that manganese sulfate monohydrate obtained through high-temperature crystallization is put into a rotary kiln and is burned with methyl alcohol, hydroxyl ions discharged after temperature increment and a burning value are mixed into powder-crystal-shaped manganese sulfate, and magnesium ions, potassium ions and sodium ions are caught and then are coked; the dried and coked magnesium-potassium-sodium mixture is put into a dissolution kettle, deionized water is added, dissolution and filtering are carried out, and un-dissolved substances (coked magnesium-potassium-sodium granules) are separated out; a qualified manganese sulfate solution is sent to a secondary high-temperature crystallizer and crystallized, a manganese sulfate hydrated crystal is obtained, then the product is sent and dried, and the qualified manganese sulfate is obtained. The preparing method is simplein step and easy to operate, the temperature and the pH value are not required to be strictly controlled, a large quantity of high-purity impunity removing medicaments are also not required to be consumed, and through the coking effect and different dissolution degrees of all impurities, the impurities are filtered out and removed out, the impunity removing effect is remarkable, secondary pollution on the environment can be avoided, the production cost is low, and industrialization scale production is easy to achieve.