A new complex [Co(Htmidc)(H2O)2]n (1) based on 2-(1H-tetrazol-1-methyl)-1H-imidazole-4,5-dicarboxylic acid (H3tmidc) has been synthesized by reacting CoSO4·7H2O with H3tmidc. Its structure, chemical component and properties were determined by single-crystal X-ray diffraction, element analysis, XPS, UV Vis spectra and FS spectra. The results show that complex 1 exhibits one-dimensional structure in which Co(II) ions are bridged by tetradentate Htmidc2− ligands with two carboxylate oxygen atoms and two imidazole nitrogen atoms. The fluorescence spectrum reveals that complex 1 can significantly quench the fluorescence intensity of BSA, which indicates that it has good ability in binding with BSA. The interaction between complex 1 and BSA is a static quenching process with formation of one binding site. In addition, the synchronous fluorescence spectrum suggested that the conformations of both tryptophan and tyrosine residues in the BSA have changed during the interaction of complex 1 with BSA.