The invention discloses a preparation method of a lithium battery electrode material alpha-Fe2O3 nanosphere. The specific steps include: dissolving potassium chlorate and ferrous sulfate in deionizedwater to obtain a mixed solution, using a coconut diethanolamide solution to adjust the pH value of the solution to 10, putting the mixed solution in a high-pressure reaction kettle, performing heating at 120DEG C-150DEG C for 10h-14h, and then taking the product out of the reaction kettle; conducting repeated ultrasonic washing with deionized water for 20min-50min, and separating the precipitateproduct; drying the precipitate product, and performing calcinations at 350DEG C in oxygen atmosphere for 51h, thus obtaining the final black brown powder product. The Fe2O3 prepared by the method provided by the invention has cheap and easily available raw materials, also can have a wider electrochemical window and better rate performance under the same conditions, and has good cycle performance.