The work aims to explore the effects of introduced carbonxyl content of glucosamine molecules on the properties of chitosan with low molecular weight oxidized by laccase-TEMPO (TEMPO is short for 2,2,6,6- tetramethyl-1-piperidinyloxy) system, for the purpose of broadening the application of chitosan in packaging area. The content of sodium ions in the samples to be detected with high-performance ion chromatography (HPIC) was used to characterize the carboxyl group content of the sample. The improvement degree of physical and chemical properties of chitosan was characterized by detecting the moisture absorbability and retentivity and oxidation resistance of the samples. The introduced carbonxyl of chitosan molecules could help to improve the moisture absorbability and retentivity. The rate of moisture absorption of oxidation products in saturated potassium carbonate and saturated ammonium sulfate solutions for 60 h could respectively reach up to 63.0% and 18.4%, and the rate of moisture retention was 5.7%. However, when the oxidation degree exceeded 45.31%, the moisture absorbability and retentivity remained unchanged. The more addition of TEMPO is, the more carboxyl content of oxidation products is. The introduced carboxyl groups can improve the moisture absorbability and retentivity of chitosan’s oxidation products. The increase in the carbonxyl content of glucosamine molecules will improve the oxidation resistance of chitosan. Such improvement is of far-reaching importance for the chitosan to be applied in the packaging materials.