Abstract: The composition and morphology of two kinds of circulating fluidized bed fly ash (CFBFA) in Xinjiang were investigated by X-ray diffraction, scanning electron microscope and chemical analysis methods. The CFBFA were modified by adding FeCl₃ and AlCl₃ water solution, the particle size and dosages of these modified CFBFA on the treatment efficiency of oil-water separation wastewater from Xinjiang Karamay polymer flooding oilfield were also investigated. The experiment results showed that these CFBFA has the contents of SiO₂, A1₂O₃, Fe₂O₃, CaO and MgO accounting for more than 90% of the total weight, lower content of glass phase, irregular particle shape and rough surface; the particle size of the modified CFBFA below 0.074 mm with good removal effect, the removal rate increased with the increasing of the dosage; when the dosage was 0.1 g/mL in the wastewater, the removal rate reached more than 90%.