To achieve efficient gene delivery to the tumor after intravenous administration, biodegradable poly(2-(2aminoethyoxy)ethoxy)phosphazene (PAEP) was modified by lactobionic acid, bearing a galactose group as a targeting ligand. Galactosylated poly(2-(2-aminoethyoxy)ethoxy)phosphazene (Gal-PAEP) with 4.9% substitution degree of galactose could condense pDNA into nanoparticles with a size around 130 nm at the polymer/DNA ratio (N/P) of 2-40. For BEL-7402 cells, the in vitro transfection efficiency of gal-PAEP/DNA complex nanoparticles (gal-PACNs) was much higher than that of the PAEP/DNA complex nanoparticles (PACNs). MTT assay indicated that the cytotoxicity of PACNs significantly decreased after conjugating with the galactose moiety. Gal-PACNs displayed the selective gene expression in the tumor and liver with relatively low gene expression in the lung or other organs compared with PACNs. These results suggested that gal-PACNs could be a promising targeting gene carrier to deliver a therapeutic gene in future.