A method for preparing a ternary single crystal positive electrode material, comprising the following steps: mixing a ternary polycrystalline micropowder, raising a temperature, carrying out a primary sintering, and lowering the temperature to obtain an intermediate; subjecting the intermediate to jet pulverization to obtain a single crystal material, washing the single crystal material with water, and centrifugally drying the single crystal material to obtain a material with a residual alkali content of less than 1500 ppm; and adding a coating agent to the material, raising a temperature, carrying out a secondary sintering, and lowering the temperature to obtain the ternary single crystal positive electrode material; wherein the coating agent is at least one of an oxide, hydroxide and salt of a metal, or an oxide and fluoride of a non-metal, or a corresponding acid and salt of the non-metal; the metal is at least one of Al, Ce, Y, Zn, Cr, Nb, Mg, La, Sr, Zr, Sn, Na, Ca, Sb, V, and W; and the non-metal is at least one of B, P, F, C, and S, with aluminum hydroxide being excluded; wherein in step, the ternary polycrystalline micropowder is an unqualified product produced by means of mechanical grinding of the ternary polycrystalline material during crushing, which is a by-product produced during crushing of the ternary polycrystalline material; and a chemical formula of the ternary polycrystalline micropowder is LiNi x Co y Mn z O 2, with 0.5 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.4, 0.05 ≤ z ≤ 0.4, and x + y + z = 1; wherein in step, requirements for the particle size of the single crystal material are: a D v 50 of 2.0-4.0 μm and a D v 99 of less than 10 μm. mixing a ternary polycrystalline micropowder, raising a temperature, carrying out a primary sintering, and lowering the temperature to obtain an intermediate; subjecting the intermediate to jet pulverization to obtain a single crystal material, washing the single crystal material with water, and centrifugally drying the single crystal material to obtain a material with a residual alkali content of less than 1500 ppm; and adding a coating agent to the material, raising a temperature, carrying out a secondary sintering, and lowering the temperature to obtain the ternary single crystal positive electrode material; wherein the coating agent is at least one of an oxide, hydroxide and salt of a metal, or an oxide and fluoride of a non-metal, or a corresponding acid and salt of the non-metal; the metal is at least one of Al, Ce, Y, Zn, Cr, Nb, Mg, La, Sr, Zr, Sn, Na, Ca, Sb, V, and W; and the non-metal is at least one of B, P, F, C, and S, with aluminum hydroxide being excluded; wherein in step, the ternary polycrystalline micropowder is an unqualified product produced by means of mechanical grinding of the ternary polycrystalline material during crushing, which is a by-product produced during crushing of the ternary polycrystalline material; and a chemical formula of the ternary polycrystalline micropowder is LiNi x Co y Mn z O 2, with 0.5 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.4, 0.05 ≤ z ≤ 0.4, and x + y + z = 1; wherein in step, requirements for the particle size of the single crystal material are: a D v 50 of 2.0-4.0 μm and a D v 99 of less than 10 μm. wherein in step, the ternary polycrystalline micropowder is an unqualified product produced by means of mechanical grinding of the ternary polycrystalline material during crushing, which is a by-product produced during crushing of the ternary polycrystalline material; and a chemical formula of the ternary polycrystalline micropowder is LiNi x Co y Mn z O 2, with 0.5 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.4, 0.05 ≤ z ≤ 0.4, and x + y + z = 1; wherein in step, requirements for the particle size of the single crystal material are: a D v 50 of 2.0-4.0 μm and a D v 99 of less than 10 μm.