A method for producing battery-grade nickel sulfate by using laterite nickel ore, comprising the following steps: obtaining lump ore and sediment ore by sorting the laterite nickel ore; wherein the lump ore and the sediment ore are sorted according to a particle size, where a particle size of the lump ore is greater than 10 mm, and a particle size of the sediment ore is less than 10 mm; obtaining a crude nickel sulfate solution A by crushing the lump ore, and then performing heap leaching; obtaining high chromium ore, low iron, high magnesium ore, and high iron, low magnesium ore by separating the sediment ore, and obtaining low nickel matte by drying, roasting, reducing, and sulfurating the low iron, high magnesium ore; wherein the high chromium ore comprises 30-40% of chromium and 0.1-0.2% of nickel; the low iron, high magnesium ore is mainly garnierite and comprises 1.5-2.1% of nickel, 15-25% of magnesium, 8-25% of iron, and 35-50% of silicon; and the high iron, low magnesium ore is mainly limonite and comprises 0.8-1.3% of nickel, 30-50% of iron, 0.1-10% of magnesium, and 10-30% of silicon; obtaining a crude nickel sulfate solution B by blowing and performing water extraction on the low nickel matte, and then performing oxygen pressure leaching; obtaining a crude nickel sulfate solution C by performing pressure leaching on the high iron, low magnesium ore; and obtaining battery-grade nickel sulfate by performing extraction on the crude nickel sulfate solution A, the crude nickel sulfate solution B, and the crude nickel sulfate solution C, and then evaporating and crystallizing; wherein, in the battery-grade nickel sulfate, a content of Mg < 0.002%, a content of Si < 0.001%, a content of magnetic substance < 0.08%, and a content of Co < 0.002%. obtaining lump ore and sediment ore by sorting the laterite nickel ore; wherein the lump ore and the sediment ore are sorted according to a particle size, where a particle size of the lump ore is greater than 10 mm, and a particle size of the sediment ore is less than 10 mm; obtaining a crude nickel sulfate solution A by crushing the lump ore, and then performing heap leaching; obtaining high chromium ore, low iron, high magnesium ore, and high iron, low magnesium ore by separating the sediment ore, and obtaining low nickel matte by drying, roasting, reducing, and sulfurating the low iron, high magnesium ore; wherein the high chromium ore comprises 30-40% of chromium and 0.1-0.2% of nickel; the low iron, high magnesium ore is mainly garnierite and comprises 1.5-2.1% of nickel, 15-25% of magnesium, 8-25% of iron, and 35-50% of silicon; and the high iron, low magnesium ore is mainly limonite and comprises 0.8-1.3% of nickel, 30-50% of iron, 0.1-10% of magnesium, and 10-30% of silicon; obtaining a crude nickel sulfate solution B by blowing and performing water extraction on the low nickel matte, and then performing oxygen pressure leaching; obtaining a crude nickel sulfate solution C by performing pressure leaching on the high iron, low magnesium ore; and obtaining battery-grade nickel sulfate by performing extraction on the crude nickel sulfate solution A, the crude nickel sulfate solution B, and the crude nickel sulfate solution C, and then evaporating and crystallizing; wherein, in the battery-grade nickel sulfate, a content of Mg < 0.002%, a content of Si < 0.001%, a content of magnetic substance < 0.08%, and a content of Co < 0.002%.