Amino-modified tetrapod-like ZnO nanostructures were tried as novel carriers for mammalian cell transfections. The nanostructures consisted of four needle-shaped tetrahedrally arranged legs connected at the center. After silica coating and amino modification, ZnO nanostructures complexes bound plasmid DNA through electrostatic interactions in aqueous solution. When mixed with cells, DNA-nanostructures attached easily onto cell membranes and entered the cells for gene expressions. Due to high positive charge densities on surfaces and needle-shaped tetrahedral structures, functionalized ZnO used as carriers for cell transfections with both high transfection efficiency and little cytotoxicity. And a possible transfection machamism was proposed in this report.