This study provided an experimental evidence for the use of cyclen (1, 4, 7, 10-tetraazacyclododecane)-based polymer for gene delivery. The interesting interaction of the polymer with plasmid DNA was studied by using fluorescence titration, circular dichroism spectra, agarose gel electrophoresis and atomic force microscopy. It was found that polyplex was formed between the polycation and plasmid DNA. The results demonstrated that the cyclen-based polymer could act as non-viral gene vector with relatively low cytotoxicity.