Abstract: To prepare a new clarifying agent instead of SO2 in sugarcane industry,carboxymethyl chitosan was prepared in this study using chloroacetic acid(CA) as a modifier and chitosan(CTS) as raw material under treatment of microwave radiation. Optimal preparation conditions of carboxymethyl chitosan were evaluated by the decolourization ratios and the purity differences to cane juice clarification,and the product was analyzed by scanning electron microscope(SEM),infra-red spectrum(FT-IR) and nuclear magnetic resonance(1H-NMR).The results indicated that under treatment of mNa OH∶ mCTS=5∶1,microwave power 600 W,treatment time 12 min,mCA∶mCTS=6∶1,the product was proved to be N,O-carboxymethyl chitosan,and its water-solubility,adsorption range of charged colloids in cane juice and the electricity neutralization were all improved. The decolourization ratio and the purity difference of the new clarifying agent used in cane juice clarification were 50.45% and 1.63%,respectively. According to data obtained from sulfitation process, the results indicated that carboxymethyl chitosan could replace SO2 in cane juice clarification.