Ten pyrazole derivatives were synthesized and characterized by IR spectra, 1H-NMR spectra and MS spectra. The coordination reaction of the derivatives with CuCl2. And ten novel Cu(Ⅱ) complexes with the derivatives were prepared and characterized by IR spectra and elemental analysis. The catalytic degradation of methyl orange aqueous solution was investigated using the complexes as catalysis in presence H2O2 by HPLC method and Vis-spectrophotometry. The result of characterization showed that there are four coordination sites around Cu(Ⅱ) in all complexes, which are respectively occupied by one sulfur atom (from the derivative), one nitrogen atom(from the derivative), one oxygen atom( from the H2O) and one chloro atom(from the Cl-). The degradation of methyl orange indicated that all the complexes show the properties of enzyme activity. And the main degradation product determined was maleic acid. And the mechanism of the catalysis was deduced.