Amine group at glucosamine unit of chitosan is a very important moiety, because it presents a strong positive chare and high reactivity. Especially, its positive charge can form the complex with plasmid. In this study, we revealed characterization as a gene carrier of low molecular water soluble chitosan(LMWSC) having various molecular weight, 10K, 20K, 50K. used all LMWSCs are highly water-soluble and can effectively form complexes with plasmids in physiological buffer. In the evaluation of protective effect of LMWSC, LMWSC protected the DNA efficiently from DNase I. The transfection efficiency of LMWSCs (10K, 20K, and 50K) mediated transfection to 293T cells was significantly higher than that of naked DNA. From MTT assay, all LMWSC complexes showed negligible cytotoxicity for 293T cells. Finally, the efficiency of LMWSC mediated transfection to 293T cells was significantly higher than that of naked DNA.