Ceria-zirconia composites at different molar ratios were synthesized. Several methods were used to characterize these composites, including X-ray photoelectron spectroscopy, surface area and surface acid-base property detection. A one-step method for isolation and identification of phosphopeptides from peptide mixture was created using these ceria-zirconia composites. Using tryptic digest of standard phosphorylated protein, we have shown that these enrichment and dephosphorylation activities are effective. The adsorption capacity and catalytic property of ceria-zirconia composites at different molar ratios and calcinated temperatures were studied. In combination with MALDI-TOF-based peptide mass finger printing technique, we have established a method to utilize the enrichment/dephosphorylation dual properties of these ceria-zirconia composites for the analysis of phosphoprotein in nonfat milk successfully.