Histone H1 contributes to condense nucleosome into super-structure during the transformation of chromatin into chromosome. It is shown in this rep or t that the fusion protein HNHG with the core of C-terminus of histone H1(0) expressed in BL21 (DE3) could also condense the plasmid DNA, just as histones did in nucleus. Under electron microscope, plasmid DNA condensed and supercoiled after t he addition of HNHG, in contrast to plasmid DNA control. This specific ability of the fusion protein HNHG of binding and condensing plasmids could be utilized to construct novel exogenous gene delivery systems. HNHG would be a promising candidate for gene delivery.