A novel cadmium(Ⅱ) coordination polymer {[Cd(1,5-nds)(Him)2(H2O)]·2H2O}n (1,5-nds = naphthalene-1,5-disulfonate and Him = imidazole) was synthesized based on the reaction of cadmium oxide and 1,5-naphthalenedisulfonic acid firstly, and then mixed with imidazole in methanol medium. Its structure was characterized by elemental analysis, IR and TGA, respectively. The crystal structure was determined by single-crystal X-ray diffraction. The crystal belongs to the triclinic system, space group P, with a = 8.5420(10), b = 10.2570(10), c = 13.361(2)(A), α = 100.704 (2), β = 100.195(2), γ = 108.873(3)°, C16H20Cd N4O9S2, Mr = 588.91, V = 1.0524(2) nm3, Dc = 1.858 g/cm3, Z = 2, F(000) = 592, μ= 1.294 mm-1, R = 0.0397 and wR = 0.1007 for 3180 observed reflections (I > 2σ(I)). Structural analysis shows that the cadmiun atom is coordinated with four oxygen atoms from three 1,5-nds and one water molecule together with two nitrogen atoms from two imidazoles, giving a distorted octahedral coordination geometry. The molecules are linked to form a two-dimensional coordination polymer based on bridging ligands of naphthalene-1,5-disulfonate anions, the sheets of which are then interacted via hydrogen bonds, leading to a three-dimensional network structure.