The invention relates to a production method of the polyaluminium chloride, which takes wastes as main materials, therefore, the production method is very beneficial to the environment and resource protection. The production method of the polyaluminium chloride comprises the following steps: a. the first aluminum-containing material reacts with the hydrochloric acid solution to obtain the reaction mother liquor; and b. the reaction mother liquor reacts with the second aluminum-containing material, then curing and depositing, the upper layer clear liquid is taken out, namely the polyaluminium chloride solution. The first aluminum-containing material and the second aluminum-containing material comprises the aluminum-containing sludge, the acidity of the reaction mother liquor in the step a is 9% to 12%, the content of Al2O3 is more than or equal to 8.0%, in the step b, the reaction mother liquor and the aluminum-containing material react under the condition of 110 to 120 DEG C and 0.2 to 0.4MPa. The invention completely utilizes the industrial waste, and saves a mass of mineral resources and industrial hydrochloric acid, the production process focuses on the recycling utilization of the industrial waste, which is very beneficial to the environment and resource protection, and simultaneously the production costs of the PAC product are significantly reduced.