A cobalt metal-organic framework constructed by 4-(4-pyridyl)-benzoic acid was used as the precursor to afford a series of Co nanoparticles embedded and N/O-doped porous carbon materials CoNOC-T-c-t (where T-c represents the carbonization temperature and t represents the carbonization time), which possess high surface area, hierarchically micro-, meso- and macropores, and high graphitization as well as the uniformly enchased N-Co-O catalytic active sites derived from pyridine nitrogen atom and chelating carboxylate coordinated octahedral cobalt (II) center. These CoNOC-T-c-t porous carbon nanostructures have demonstrated prominent catalytic activities toward oxygen reduction reaction (ORR) in alkaline medium. Compared with commercial Pt/C catalyst, the CoNOC-800-1 (annealed at 800 degrees C for 1 h) exhibits excellent selectivity via an efficient four-electron-dominant ORR process, as well as the superior durability and methanol tolerance, making it a cost-effective Pt-free ORR electrocatalyst. More importantly, the novelly designed N-Co-O catalytic active sites are proposed and well demonstrated by experiments, which provides a promising approach to develop heteroatom-doped carbon-based electrocatalytic materials.