Exposure of the active sites directly determines the catalytic activity of porous carbon electrocatalysts for oxygen reduction reaction (ORR). How to maximally expose these active sites in as-synthesized carbons is still a great challenge. Here we propose an efficient strategy to maximally expose the active sites of porous carbon catalysts, in which we use core-shell ZIF-8@ZnCo-ZIF (op-ZnCo-ZIF) as a precursor to synthesize Co, N-doped carbon catalysts (op-ZnCo-950) by pyrolysis. The low boiling metal Zn in the core-shell template can serve as the activation agent to yield the micropores and mesopores, and the cobalt in the shell is therefore dispersed well in the surface of as-synthesized carbons during the pyrolysis. As a result, the resultant op-ZnCo-950 exhibits a relatively high catalytic activity towards ORR with a half-wave potential of 0.846 V (vs RHE), and the higher methanol resistance and better stability than 20% Pt/C. This work provides an efficient core-shell template strategy for synthesis of carbon catalysts with highly exposed active sites for electrochemical applications including ORR, hydrogen evolution reaction and oxygen evolution reaction.