Self-assembly of naphthalene phosphonate carboxylate ligand and cobalt(Ⅱ) chloride hexahydrate, 1D coordination polymer, namely ［Co(5-pncee)(4,4′-bpy)(H2O)3(5-pnceeH2)］·2H2O(1) (5-pnceeH2=5-phosphono -naphthalene-1-carboxylic acid ethyl ester, 4,4′-bpy=4,4′-bipyridinyl) was hydrothermally synthesized and characterized by single-crystal X-ray diffraction, EA, FT-IR spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TG-DTG). Structure analyses reveal that compound 1 crystallized in the triclinic system, space group of P1, a=0.824 06(6) nm, b=1.014 48(9) nm, c=1.151 44(8) nm. It shows a linear chain structure. The neighboring chains are connected by moderately strong hydrogen bonds forming a supramolecular layer. The interlayer spaces are filled with the organic groups of the phosphonate ligands. Magnetic properties were investigated for compound 1, it is found that there is spin orbit coupling and/or antiferromagnetic interaction between Co(II) ions.