The invention discloses a lithium sulfur battery cathode material and preparation method thereof, and belongs to the technical field of lithium battery cathode material preparation. The preparation method of the lithium sulfur battery cathode is as follows: uniformly mixing polymer fiber and elemental sulfur, placing the mixed polymer fiber and elemental sulfur in a closed reaction container, raising temperature to 200-500 DEG.C in the inert gas atmosphere, keeping temperature for 0.5-12 hours, and performing cooling to obtain the lithium sulfur battery cathode material. The diameter of the polymer fiber is 100-5000nm, and the mass proportion of the polymer fiber to the elemental sulfur is 1: 1-1: 10. The lithium sulfur battery cathode material disclosed by the invention uses the polymer fiber with a quasi-one-dimensional nano-structure as a carrier, the obtained lithium sulfur battery cathode material is regular in feature; in the charging/discharging process of the lithium sulfur battery, a diffusion path of the lithium ion in the cathode material is about the size of the fiber semi-diameter, and the diffusion path is short; therefore, the lithium sulfur battery cathode material has high first coulombic efficiency and good cyclic stability in large current charging/discharging.