A novel Ni (II) coordination polymer ［Ni(pdc)(bib)(H2O)］n(Ni-CP) was synthesised by solvothermal method with 3,5-pyridyl dicarboxylic acid (3,5-H2pdc), 1, 4-bis (1-imidazolyl) benzene (bib) and Ni(NO3)2, and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric, IR spectroscopic and fluorescence spectroscopy analysis. The results show that Ni-CP crystallized as a monoclinic system with C2/c space group. The asymmetric unit of Ni-CP was comprised of one Ni(II), two half bib ligands, one completely deprotonated 3,5-pdc2- ligands and one coordinated water molecule. The environment around central Ni(II) can be described as irregular hexacoordination octahedral geometry of NiO3N3. The bib and 3,5-pdc2- ligands were bridged by the bidentate coordination mode in the μ2-η1∶η1 fashion and the tridentate coordination mode in the μ3-η1∶η1∶η1 fashion to form a three-dimensional network framework. From a topological point of view, the two-dimensional frame structure can be simplified to a 3-connected topology with a Schlfli symbol (4·82). We consider the 3,5-pdc2- ligands and Ni(II) as nodes and the bib ligands as connectors, forming a three-dimensional structure can be simplified to a 3,5-connected double nodes with topological symbols (4·6·8)(4·62·87). The porosity of Ni-CP is 17.4%. Ni-CP could selectively detect Fe3+, CrO2-4 and Cr2O2-7 with detection limits of 4.275×10-5, 2.681×10-5, 2.681×10-5 mol/L, respectively, and have a high quenching rate.