The invention discloses a lithium sulfur battery cathode material, a preparation method thereof, and lithium sulfur batteries. The lithium sulfur battery cathode material is composed of an inner core and a housing used for coating the inner core; the inner core is a composite material of porous carbon and a sulfur-containing substance; the sulfur-containing substance is elemental sulfur and/or a polysulfide; pore diameter of porous carbon ranges from 2 to 100nm; porous carbon is filled with the sulfur-containing substance; the housing is a compact carbon layer or a micropore carbon layer; the composite material of porous carbon and the sulfur-containing substance of the lithium sulfur battery cathode material is coated with the compact carbon layer or the micropore carbon layer; almost no pore is observed among carbon in the compact carbon layer, or particle size of micropore carbon is less than 2nm, so that diffusion of polysulfide lithium through the compact carbon layer or the micropore carbon layer into an electrolyte is impossible, dissolving of polysulfide lithium is inhibited, and capacity fading of lithium sulfur batteries in charge-discharge cycles is improved. Raw materials used in the preparation method are cheap and easily available; processes are simple; and industrialized production can be easily realized.