This study was investigated in order to develop recovery system of phosphate and ferric chloride from precoagulated sludge with ferric chloride. Experiments were conducted to clear the following points, Dextraction efficiency of phosphate from pre-coagulated sludge with ferric chloride by introducing H₂S gas into sludge, 2) recovery of phosphate from the supernatant after the extraction using Ca (OH) ₂, 3) simultaneous recovery of ferric chloride and H₂S from the residue after the extraction by adding HCl solution and 4) the mass balance of suspended solid, phosphorus, iron and sulfur in this total system. As the result of mass balance in this system, 40% of phosphate and 73.1% of ferric chloride from precoagulated sludge with ferric chloride and 47.2% of introduced H₂S gas were recovered at the optimum experimental condition.