The invention relates to an urchin-like lithium ion battery positive electrode material preparation method, which comprises: uniformly dissolving NH4VO3 in a solvent containing ethylene glycol and water to obtain a NH4VO3 solution; adjusting the pH value of the NH4VO3 solution by using an oxalic acid solution, and carrying out a reaction in an ultrasonic environment to obtain a solution A; placingthe solution A in a reaction kettle with a polytetrafluoroethylene lining, arranging the reaction kettle in a homogeneous hydrothermal reaction, and carrying out a reaction to obtain a suspension; and naturally cooling to a room temperature after completing the reaction, alternately washing respectively with water and ethanol, and carrying out vacuum drying to obtain the urchin-like lithium ion battery positive electrode material. According to the present invention, the lithium ion battery positive electrode material with the urchin morphology is synthesized by adjusting the types of the solvents during the hydrothermal reaction so as to improve the structure and the performance of NH4V3O8, wherein the problem that the electrode active substance can not sufficiently contact the electrolyte can be effectively solved through the urchin morphology so as to effectively solve the contact area between the electrode active substance and the electrolyte, promote the rapid transfer of lithiumions, and improve the electrochemical property of NH4V3O8.