Two-dimensional Co3O4 nanosheets dotted with Au nanoparticles were synthesized on the carbon gas diffusion layer as a bifunctional catalyst for Li-O-2 batteries by thermal evaporation and low-temperature calcination. The two-dimensional Co3O4 nanosheets improved the catalytic activity and Au nanoparticles provided additional nucleation sites for the Li2O2 growth in the process of discharge, thus allowing the uniform formation of Li2O2. Moreover, the size and distribution of Au nanoparticles were tuned by evaporating Au in different thicknesses. The catalytic performance of the Co3O4-Au hybrid was improved due to the synergetic effects of both materials and the improvements were closely associated with the size and distribution of Au nanoparticles. When the rationally designed catalyst was used as a cathode catalyst in Li-oxygen batteries, it lowered the polarization effect during cycling and realized the stable cyclability for 70 cycles at a limited capacity of 1000 mA h g(-1).