Five new mixed ligand complexes Cu(X PTLA)phe[PTLA=2 (COO)C6H4CONHC6H4,X=H,2 Cl,2 CH3,2 OCH3,4 OCH2CH3,Phe=β phenylalanine] were synthesized and characterized by means of elemental analysis, infrared and ultraviolet as well as thermogravimetical analysis. It is indicated that in mixed ligand complexes coordination occurs through carboxylate oxygen, oxygen of amino in 2 [(substituted phenylamino) carbonyl] benzoic acid and carboxyl oxygen, nitrogen of amino in amino acid.Stereo configuration of the complex is plane square. Three ways,MacCllum and Tammer ,Coats and Redfern and Zsako methods, were adopted to calculate the values of the apparent decomposition activation energies, the activation entropies, the reaction orders and the frequency factors, respectively. The results show that the reaction orders are all 2/3. Studies of the mechanism of these reactions state that these reactions all fit the kinetic equation 1-(1-α)1/3=kt.The changes of activation energies and activation entropies were discussed.