CeO2-ZrO2 composite oxides (CZ) were prepared through a co-precipitation method using magnesium hydrogen carbonate as the precipitating agent which was prepared from the cheap dolomite ores. The effects of peroxide oxidation time on the properties of CZs were studied. The crystal structures, surface areas, surface micromorphologies, redox performances and oxygen storage capacities of the as-synthesized CZs were studied by XRD, BET, SEM, TPR and oxygen pulse adsorption techniques, respectively. The results show that the addition of peroxide increases CZ’s surface area, improves thermal stability, suppresses phase separation, and also increases the active surface oxygen amount. The surface area, aging property and oxygen storage capacity increase with prolonging the oxidation time and they reach to the maximum values at 30 min, when the sample’s 600 oC calcined fresh specific surface area, 1000 oC aged specific surface area as well as 500 oC oxygen storage capacity could reach 111.3 m2/g, 32.9 m2/g and 315 μmol O2/g, respectively. However, their values change little when prolonging the oxidation time further.