The complexes of DL-homocysteic acid (DLH) with Na+, Cu2+, Zn2+ and Ni2+ were synthesized and elemental analyses were used to detect the compositions of these complexes. FTIR spectroscopy was employed to study these coordination structures. The results indicated that all the amino, carboxyl and sulfonate groups of DLH may have direct or indirect interactions with Na+, Cu2+, Zn2+ and Ni2+. The bond strength between metal ions and oxygen of the carboxyl as well as that between metal ions and the amino group are in the order of Cu2+ > Zn2+ > Ni2+, where carboxyl with different ions may take different coordination modes in these complexes, as indicated from the difference between its asymmetric and symmetric stretching vibration.