The invention relates to an application of an ion exchange membrane in a lithium-sulfur secondary battery. The ion exchange membrane is prepared by taking polyvinylidene fluoride organic polymer resin and sulfonated graphene as raw materials through a blade-coating film-forming method, wherein the mass ratio of polyvinylidene fluoride organic polymer resin to sulfonated graphene is (1-15) to 1; the pore diameter is 0.1-10nm; and the porosity is 30-60%. According to the membrane, selectivity conduction of polysulfide ions and lithium ions can be effectively realized through ion exchange groups on the sulfonated graphene, the ion penetration selectivity of the membrane is maintained, and ion transfer and blocking of polysulfide ions can be realized without depending on a special lattice structure; and the membrane material is simple in preparation method and low in cost, and batch production can be realized easily, so that the machining method and the selection range of the membrane material of the lithium-sulfur secondary battery are expanded.