In this paper, we used fly ash as the main raw material, under the conditions of the water bath to prepare three kind of modified fly ash: Na-fly ash, K-fly ash and Ca-fly ash, and then we studied their removal of chromium ions and tested the effects of dosage, temperature, mixing time and pH value of modified fly ash on characteristic of composite adsorbent. The experimental results show that: in the three kind of modified fly ash, Ca-fly ash has strong adhesive properties, when it was used to process Chromium-containing wastewater, the removal rate of Chromium ion reached 39.32%, and when the modified fly ash-composite Chitosan was used to process Chromium-containing wastewater, the adsorption rate on Cr (VI) reached 40.67%.