Abstract: Aluminum-extracting residue from fly ash is the waste residue produced by "one-step acid solution of high aluminum ash extraction of alumina", which mainly contains silica, alumina, aluminum chloride, unburned carbon and other substances. At present, the unburned carbon limits the utilization of aluminum-extracting residue from fly ash in building materials. The flotation method is very effective in removing the unburned carbon and reducing the ignition loss of aluminum-extracting residue from fly ash. In order to improve flotation efficiency and look for the optimal dosage of flotation reagents, Six Sigma experimental design and response surface analysis method were adopted to build up the ignition loss model and the unburned carbon recovery model for optimal addition amounts of light diesel oil, oleic acid, No.2 oil and Sodium polyacrylate. The results show the best flotation operating conditions are 4000 g/t light diesel oil, 100 g/t No.2 oil and 500 g/t polyacrylate sodium. Under these operating conditions, the ignition loss of aluminum-extracting residue from fly as is decreased to below 1%, and the recovery of unburned carbon is 83.37%.