The invention discloses a high-purity crystalline aluminum chloride preparation method. The high-purity crystalline aluminum chloride preparation method comprises the following steps: feeding hydrochloric gas into an aluminium chloride solution or an aluminium sulfate solution, controlling the concentration of hydrochloric acid in the solution to be 7.5-12mol/L, separating by crystallization, and filtering, thus obtaining high-purity crystalline aluminum chloride. The high-purity crystalline aluminum chloride preparation method has the advantages that the corrosion to equipment caused by an evaporative crystallization process is avoided, the process is simple, the energy consumption is low, few wastes are generated, the obtained crystalline aluminum chloride is high in purity, and the production requirements of metallurgical-grade aluminium oxide can be directly satisfied.