Cu(4-ATz)₂Cl₂?H₂O was synthesized with 4-amino-1,2,4-triazole (4-ATz) and copper chloride dihydrate, and was characterized by elemental analysis, IR and melting point determination. The thermal behaviors and nonisothermal demposition reaction kinetics of the complex were studied by differential scanning calorimetry (DSC) and thermogravimetry and derivative thermogravimetry (TG-DTG) techniques. The results show that the mole ratio of metal to ligand is 12. The reaction mechanism of the main exothermic decomposition process of the complex is classified as chemical reaction and f(α)=32（1-α）［-ln(1-α)］^1/3, and the kinetic equation is obtained as: dα/dt=10^21.83×32（1-α）［-ln(1-α)］^1/3×exp(-2.75×104/T).