The invention discloses nearly cubic lithium vanadium phosphate and a preparation method thereof, a lithium-ion battery and a positive electrode of the lithium-ion battery. The preparation method comprises the steps of (1) adding a vanadium source and a reducing agent to deionized water for stirring and dissolving, and then adding a phosphorus source and lithium nitrate for further stirring to obtain a solution A; (2) evenly stirring and dispersing hexadecyl trimethyl ammonium bromide (CTAB) into the deionized water to obtain a solution B; (3) dropwise adding the solution B to the solution A, adding ethylene glycol and urea for stirring for 22-25 hours to prepare a solution C; (4) carrying out hydrothermal reaction on the solution C to prepare a precursor; and (5) burning the precursor in an inert gas protection atmosphere to prepare the nearly cubic lithium vanadium phosphate. According to the method, the process is simple, the synthesis pathway is simple and controllable and micro control on the shape and the size of the material is easy to implement; and the prepared nearly cubic lithium vanadium phosphate is an excellent positive electrode material of the lithium-ion battery, so that the lithium-ion battery assembled by the positive electrode has high specific discharge capacity.