The study mainly focuses on cell transfection efficiency and cytotoxicity of a histidylated cationic copolymer in order to explore its potential as a gene carrier. A novel histidylated cationic copolymer，PEG-b-PLG-g-PEIs-HISs(GGIS)

was synthesized by free radical polymerization．The chemistry structure of GGIS was confirmed by

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H-NMR.Agarose gelelectrophoresis was performed to study the capacity of plasmid DNA condensation. Particle size and zeta potential were measured at various N/P ratios. Cytotoxicity of GGIS was determined by MTT assay in HEK 293T

Hela

BEL7402 and A549 cells lines .The transfection efficiency of GGIS was specifically evaluated and monitored by flow cytometry. When the N/P less than of 30. The size of the DNA/GGIS was approximately 100～200 nm and the zeta-potential was 10~30 mV.The MTT assay showed that the cytotoxicity of GGIS was obviously lower than PEI 25K. GGIS demonstrated significantly higher transfection efficiency than PEI 25K.Therefore

GGIS with high transfection efficiency and low cytotoxicity has great potential to be used as non-viral gene carriers．