The invention discloses a technology for preparing crystallized aluminum chloride. The technology comprises the following steps that 1, hydrolysis water is subjected to primary condensation; 2, a hydrolysis water concentrated crude product 1 obtained after the first step is subjected to secondary concentration; 3, a hydrolysis water concentrated crude product 2 obtained after the second step is subjected to tertiary concentration; 4, the temperature of a principal product hydrolysis water concentrated crude product 3 is decreased to the temperature being 45 DEG C or below, an industrial grade crystallized aluminum chloride finished product is obtained; 5, by-product hydrochloric acid treatment is performed. The operation is easy, industrial production is easy, the hydrolysis water can be efficiently utilized for extracting aluminum chloride meeting the industrial requirement, by-product diluted hydrochloride acid is treated in the extracting process, material waste is avoided, meanwhile, the technology is clean and environmentally friendly, waste materials are recycled, and economic benefits of an enterprise are increased.