Abstract: This study explored the appropriate magnesium fertilizer dosage for sweet potatoes in Xianyou County, and clarified its effects on indicators such as agronomic traits, yield, and nutrient content sweet potatoes. Five experimental treatments were set up in this study with no magnesium fertilizer（T1, control), low magnesium fertilizer（T2, MgO 19.5 kg·hm⁻²), medium magnesium fertilizer 1（T3, MgO 40.5 kg·hm⁻²), high magnesium fertilizer（T4, MgO 60.0 kg·hm⁻²), and medium magnesium fertilizer 2（T5, MgO 40.5 kg·hm⁻²). Among them, the magnesium source for T2～T4 was magnesium sulfate heptahydrate, and T5 treatment was magnesium hydroxide. The results showed that compared with no magnesium fertilizer（T1 treatment), the application of magnesium fertilizer（T2～T5 treatments）improved the agronomic traits sweet potatoes and increased the total nitrogen, total phosphorus, and magnesium content in the tubers, but slightly decreased the total potassium content. The application of magnesium fertilizer increased the sweet potato yield 1.0%～10.4% and the income by 1,052.5～12,146.3 yuan·hm⁻², with T5 treatment achieving the best yield and income increase. At the same MgO dosage, magnesium hydroxide was more effective than magnesium sulfate heptahydrate in increasing sweet potato yield and income. By establishing a model between magnesium fertilizer dosage and sweet potato yield, it was found that the sweet potato yield reached a maximum of 43,698.49 kg·hm⁻² when magnesium fertilizer dosage was 47.85 kg·hm⁻². For the acidic soils in Xianyou County, magnesium hydroxide is recommended as the preferred magnesium fertilizer for sweet cultivation, with an appropriate application rate（MgO）of 40.5 kg·hm⁻².