Abstract：Copper(II) bis(2-substituted 3-hydroxy-4-pyronate), where the substituent is CH3/C2H5/CH2OH, was synthesized by the reaction between CuCl2 and sodium 2-substituted 3-hydroxy-4-pyronate in aqueous solution, followed by recrystallizaton in water. By using elemental analysis, IR, UV, MS and EPR spectra, their chemical structures were determined to be planar square complexes with 1∶2 molar ratio of Cu to the pyronate in a molecule. The complexes were submitted to the test of preliminary toxicity and anti-hyperglycemic effect on STZ-diabetic mice. The results show that one of the complexes, copper(II) bis(2-ethyl-3-hydroxy-4-pyronate), increased the synthesis and release of the serum insulin, and lowered the blood glucose level in mice at the dose of 10 mg/kg, exhibiting good anti-hyperglycemic activity. Thecomplex was also safe with LD50 of 855.9 mg/kg in healthy mice.