The addition of inert support is important for the Cu-based oxygen carrier used in chemical looping combustion (CLC). The effects of the ZrO2 support on the stability and reactivity of Cu-based oxygen carrier were investigated using the density functional theory (DFT). First, the sintering inhibition mechanism of ZrO2 that support active CuO was investigated. The optimized Cu4O4/ZrO2 structure showed a strong interaction occurred between the Cu4O4 cluster and ZrO2(1 01) surface. The interaction prevented the migration and agglomeration of CuO. Next, the adsorption of CO on Cu4O4/ZrO2 and the mechanism of the CuO/ZrO2 reduction by CO were studied. CO mainly chemisorbed on the Cu site and ZrO2 acted as an electron donor in the adsorption system. The energy barrier of CuO/ZrO2 reduction by CO (0.79 eV) was much lower than that of the pure CuO cluster (1.44 eV), indicating that ZrO2 had a positive effect on CuO/ZrO2 reduction by CO. After CO was oxidized in the fuel reactor, the CuO was reduced into Cu. The adsorption of O-2 on Cue/ZrO2 and the most likely pathway of Cue/ZrO2 oxidation by O-2 were investigated. The adsorption of O-2 was found a strong chemisorption behavior. The energy barriers were low enough for the Cu-based oxygen carrier oxidation reaction. (C) 2016 Elsevier B.V. All rights reserved.