A new kind of nano-absorbent with the entirely novel structure, nano-absorbent of multi-cyanogunidine modified magnetic chitosan (CG-MCS nano-absorbent), has been firstly synthesized by using the functionalized chitosan and cross-linking agent with cyanoguanidine group simultaneously. The resulting nano-absorbent was characterized by means of the Fourier transform infrared spectra (FT-IR), transmission electron microscope (TEM), X-ray diffraction (XRD), elemental analysis and vibrating sample magnetometer (VSM). The resulting nano-absorbent basen on multi-cyanoguanidine modified magnetic chitosan has been demonstrated holding highly effective recovery for mercury ions, in other words, it showed both the extraordinary adsorption capacity for Hg(II) at high initial concentration and the strong removal ability for it at low concentration, the maximum adsorption capacity was up to 285 mg g(-1) and the removal percentage could reach 96% at low concentration. Meanwhile, the resulting CG-MCS nano-absorbent also showed a high selectivity adsorption for Hg(II) among coexisting heavy metals and the good regeneration performance. (C) 2013 Elsevier B.V. All rights reserved.