The invention discloses a preparation method of heteroatom doped porous graphene modified carbon fiber paper adopted as the interlayer of a lithium-sulfur battery. The heteroatom doped porous graphenemodified carbon fiber paper with a self-supporting characteristic is prepared by adopting a simple dipping and roasting method. The carbon fiber paper can be used as the interlayer material of the lithium-sulfur battery. Through physical constraint and chemical adsorption, the shuttle effect of polysulfide can be inhibited. The doping of heteroatoms has a certain catalytic effect on the reactionof the conversion of polysulfide to lithium sulfide and can promote the conversion of the polysulfide to the lithium sulfide. Therefore, the reaction kinetics of the lithium-sulfur battery is improved, and the electrochemical performance of the lithium-sulfur battery is improved.