Oxygen and sulfur dual-doped 3D interconnected hierarchical porous carbons (HPCs) were synthesized via pyrolysis followed by chemical activation of natural alginate. The results showed that both an appropriate poristy and high level of S doping lead to the excellent electrochemical performance. The optimal HPC-Na-900/S composite exhibited outstanding electrochemical performance as cathode materials for Li-S batteries. Specially, the electrochemical performances of the resultant HPC/S composites change randomly with the surface area, pore volume except porosity and surface chemistry under the testing conditions. The porosity plays a more important role than surface area as well as pore volume which are the crucial parameters in designing of porous carbon, and only the ratio of these hierarchical pores reaches a specific range, the best battery performance can be achieved. The introduction of heteroatom are also key factors that determines the performance of lithium-sulfur batteries. This insight into the relation of microstructure and surface chemistry with battery performance can help to guide better understand and rationally design porous carbon hosts. (C) 2018 The Electrochemical Society.