Abstract: A novel non-viral cationic gene delivery vector, cationic rehmannia glutinosa polysaccharide(C-RGP), was prepared by oxidation, Schiff reaction and polymerization with azidirine of rehmannia glutinosa polysaccharide (RGP). FT-IR, 1H -NMR, and thermogravimetric analysis were performed to characterize C-RGP. Particle size analysis, ζ potential measurements and agarose gel electrophoresis assay demonstrated that C-RGP could bind anionic plasmid DNA with electrostatic interaction. The cationic nanoparticle showd no significant cytotoxicity. When the mass ratio of vector to the green fluorescent protein based plasmid (pEGFP) was 18/1, C-RGP was found to have the highest in vitro transfection efficiency (90±0.25)%. RNA interference (RNAi) plasmid pshEGFR transfected with C-RGP, induced significant inhibitory effect on human epidermal growth factor receptor(hEGFR) at mRNA level (67±1.61)% in SMMC 7721 cell.