A rare heterometallic cluster-based polymer [Cu-4(Hbhea)(4)(mu (2)-OCH3) K(CH3OH))] (n) center dot(H2O) (n) (1) (H(3)bhea = 2-[bis-(2-hydroxy-ethyl)-amino]-ethanesulfonic acid), has been synthesized and structurally determined by single crystal X-ray diffraction, elemental analysis. Crystallographic unit of 1 consists of four Cu(II), four Hbhea ligands, one methanol molecule, one methanol anion, one K ion and one crystal lattice water and formed anion cluster [Cu-4(Hbhea)(4)(CH3O)](-) which further constructed a 3-D polymer by linking the six-coordination K ions.