Abstract: Chitosan(CTS) is an alkaline polysaccharide, whose aminogroup combined with proton in solution can form ammonium cations, which can take Schiff base reaction with carbonyl. Sodium carboxymethyl cellulose(CMC) is a good matrix to absorb water. Selecting CTS and CMC as matrix, adding into some inorganic salt K2CO3 and coating MnO2 outside to get the functional material. 30 g material can degrade the concentration of formaldehyde from 1 000 μg/m3 to 216 μg/m3 in a 0.08 m3 box during 24 h,and the material can be used 3 times or more. The material exhibits very good moisture absorption under a high humidity(70%RH), can reach up to 45%. Its absorption of water can improve the effect of formaldehyde absorption.