The invention discloses a preparation method and application of an elemental-sulfur-loaded spherical MoS2/graphene nano composite material. The preparation method comprises the following steps: dispersing graphene oxide into deionized water to obtain a graphene oxide aqueous solution; adding Na2MoS4 and elemental sulfur into the graphene oxide aqueous solution, refluxing the solution at the temperature of 95DEG C to obtain a solid product; and centrifugally separating, recycling and washing the solid product by utilizing deionized water, vacuum drying the solid product at the temperature of 100DEG C, and annealing the vacuum dried product in nitrogen at the temperature of 800DEG C to obtain uniform elemental sulfur-loaded spherical MoS2/graphene nano composite material in on step. The preparation method is simple in operation and low in cost; the elemental sulfur-loaded spherical MoS2/graphene nano composite material is prepared in a one-step method for the main problems in the research and actual application of a lithium-sulfur battery, a porous spherical structure which is domain on micro-pores and capable of effectively inhibiting the dispersion of multi-sulfur polymer is formed, and the performance of the lithium-sulfur battery of the composite material can be remarkably improved.