Transition metal compound(TMC)/carbon hybrids,as prospering electrocatalyst,have attracted great attention in the field of oxygen reduction reaction(ORR).Their morphology,structure and composition often play a crucial role in determining the ORR performance.In this work,we for the first time report the successful fabrication of porous core-shell Fe1-xS@N,S co-doped carbon(Fe1-xS@NSC-t,t represents etching time)by a novel in-situ self-template induced strategy using Fe3O4 nanospheres and pyrrole as sac-rificial self-template.The post-polymerization of pyrrole can be accomplished by the Fe3+released through the etching ofFe3O4 by HC1 acid.Thus,the etching time has a significant effect on the morphology,structure,composition and ORR performance of Fe1-xS@NSC-t.Based on the characterizations,we find Fe1-xS@NSC-24 can realize effective and balanced combination of Fe1-xS and NSC,possessing porous core-shell architecture,optimized structure defect,specific surface area and doped heteroatoms configurations(especially for pyridinic N,graphitic N and Fe-N structure).These features thus lead to outstanding catalytic activity and cycling stability towards ORR.Our work provides a good guidance on the design of TMC/carbon-based electrodes with unique stable morphology and optimized structure and composition.