Self-assembly of organo phosphonate ligands and transition metal cadmium salt, 1D coordination polymer, namely Cd0.5(5-pncH2)(H2O)1.5 (1) was hydrothermally synthesized and then characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Structure analyses reveal that compound 1 crystallized in the orthorhombic system, space group Pbcm, a=0.693 43(2) nm，b=0.887 153(3) nm, c=4.188 76(15) nm. Compound 1 disclose a 1D chain structure, in which the adjacent CdIIare bridged into one-dimensional zigzag chain by coordination water molecules. In the chain, there is a C-H…π action of adjacent naphthalene ring edges. The adjacent chains form a two-dimensional layered structure through the carboxyl double hydrogen bond from the organic phosphonic acid ligand, and the layers are connected into a three-dimensional supramolecular network framework through the van der Waals interactions. The thermal stability and luminescence behavior of compound 1 were also investigated.