Abstract: Fly ash was modified by the alkali washing and calcium oxide calcining method The infrared spectrometer and scanning electron microscopy were used to characterize the bond groups and morphology before and after modification fly ash. The dosage, pH, calcined temperature and adsorption time were used as variable factors to adsorb Cr (VI)-containing waste water. The results showed that the removal rate of Cr(VI) can reach 96.38% under modified fly ash dosage at 6 g/L, initial pH value at 8, secondary calcination temperature at 800℃ and the ratio with calcium oxide at 3∶1. The adsorption capacity reached 16.06 mg/g. The kinetic fitting process shows that the adsorption of Cr (VI) by the modified fly ash conformed to the pseudo-second-order kinetic equation. This process was dominated by chemical adsorption and continuous.