The poor conductivity of sulfur and shuttle effect of lithium polysulfides have been the key obstacles on the road to the application of lithium-sulfur batteries. In this study, a blanket biochar loaded with nano-Co3O4/ graphite heterostructure (Co3O4/Gr-BB) with synergistic effect is designed to improve the stability of lithiumsulfur batteries. The structural characterization shows that the surface of the Co3O4/Gr-BB is like a carpet, and Co3O4 particles of 10 nm-20 nm is evenly distributed. Next to the Co3O4 particles, there are graphite microcrystals, forming a heterogeneous structure of Co3O4/graphite. Co3O4/Gr-BB has strong LiPs adsorption ability, excellent catalytic activity and good conductivity. Thanks to the synergistic effect, Co3O4/Gr-BB with low specific surface is still has outstanding performance: it can maintain a reversible specific capacity of 431.51 mAh g-1 after 1000 cycles at a rate of 0.5 C, and the average capacity decay rate per cycle is only 0.037 %.