Three kinds of zinc complexes of biuret with different anions and crystallization water were synthesized by methanol solution reactions with zinc nitrate, zinc acetate or zinc sulfate and biuret as starting materials. The composition and structures of the complexes were characterized by means of EDTA titration, elemental analyses, FTIR spectra, and X-ray powder diffraction. The thermal decomposition of the complexes was studied. The experimental results showed that the zinc ions in the complexes were all four-coordinated by carbonyl oxygen atoms from the biuret ligands. The thermal decomposition processes of the zinc complexes included dehydration, oxidation and pyrolysis of the ligand and anions, and the final residue was zinc oxide.