Abstract: Polymeric aluminum-calcium chloride was prepared as a new inorganic flocculant instead of the prevailing polymeric aluminum chloride by which the sludge formed in wastewater treatment process is poor in dehydration. The aluminum oxide and calcium carbonate were taken as its materials and its preparation was in accordance to the steps as follows: baking them at high temperature; acid-dissolution; polymerization and dehydration. The synthesizing conditions are studied particularly and the optimal experimental parameters are thus obtained, i.e., the optimum proportion of raw materials (Al2O3 : CaCO3) is 3 : 2; the optimum time for acid-dissolution is 3 h and higher baking temperature is helpful for the synthesis process. The preliminary application of the new flocculant to waste water treatment was proved successful, and its performance was also proved superior to the prevailing polymeric aluminum chloride.