Based on the principle of shallow sediment, the highly efficient intensified calcium removal clarifier is developed on the basis of coagulation, flocculation, decalcification and sludge concentration. The equipment shell is made of steel or concrete. Through the high-efficiency mixing equipment at the front of the system, the wastewater reacts fully with coagulants and calcium removal reagents. Fine calcium sludge and colloidal substances in the wastewater are agglomerated by coagulation, and then enter the clarifier through the side-flow water distribution system.