Objective To evaluate the transfection efficiency of hepatocyte-targeting galactosylated polyethylenimine derivative Gal-Bu in rat liver cells (BRL-3A). Methods Gal-Bu was synthesized through chemical modification of PEI-Bu with galactose residue. The pDNA condensation ability of the polymer was evaluated by agarose gel electrophoresis, MTT assay was employed to detect the cytotoxicity of the polymer in BRL-3A cells, luciferase plasmid was used as the reporter gene to determine the transfection efficiency of Gal-Bu in BRL-3A cells, and competition assay of galactose was performed to investigate the hepatocyte-targeting property of Gal-Bu. Results Gel retardation assay showed complete condensation of pDNA at weight ratio ＞15. At concentrations ranging from 5 to 100 μg/mL, cytotoxicity of Gal-Bu and PEI 25 000 increased with the concentrations. Gal-Bu exhibited lower cytotoxicity than PEI 25 000 at the same concentration (P＜0.01）. The polymer performed the highest transfection efficiency at weight ratio of 50, which was 5.6 times of PEI 25 000 （P＜0.01） and was close to Lipofectamine 2000. Competition assay of galactose revealed that the transfection efficiency of Gal-Bu was significantly decreased in the presence of 100 mmol/L galactose （P＜0.01）, whereas this phenomenon was not observed on the transfection efficiency of PEI-Bu (P＞0.05). Conclusion Gal-Bu is a non-viral hepatocyte-targeting gene carrier with lower cytotoxicity and enhanced transfection efficiency, which would be a promising candidate in hepatocyte-targeting gene therapy.