A new one-dimensional mixed-valence Cu(Ⅰ)/Cu(Ⅱ) complex [Cu(bipy)(Me2dtc)CuI2]n 1 (bipy = 2,2′-bipyridine and Me2dtc = N,N-dimethyldithiocarbamate) has been synthesized under solution condition, and characterized by elemental analysis, IR spectrum, single-crystal X-ray diffraction and magnetic property. The crystal belongs to the tetragonal system, space group P4122 with a = b = 11.6504(16), c = 13.466(3) , V = 1827.8(5) 3, Z = 4, Dc = 2.389 g/cm3, Mr = 657.27, λ(MoKa) = 0.71073 , μ = 5.931 mm·1, F(000) = 1236, the final R = 0.0483 and wR = 0.1245. A total of 2102 unique reflections were collected, of which 2009 with I > 2σ(I) were observed. 1 consists of polymeric [CuII2]nnanions and [CuII(bipy)(Me2dtc)]+ cations. It is interesting that the cations of 1 interact through π-π stacking interactions after rotating 90° to form one-dimensional chains parallel to the anion chains. The magnetic study indicates antiferromagnetic behavior for this complex.