The invention discloses a 
sulfur / carbon 
composite material and a preparation method thereof. Nanometer 
sulfur is uniformly filled in a pore path of a carbon material in the 
sulfur / carbon 
composite material to form the nanometer sulfur particle / carbon 
composite material. The preparation method comprises the following steps of: (1) reacting an aluminum 
sulfide solution with a sulfur source to generate an aluminum 
polysulfide solution; (2) adding a surface 
active agent and the carbon material into the aluminum 
polysulfide solution, uniformly stirring the resulting product, placing the uniformly stirred solution in an ultrasonic cleaner to carry out 
ultrasonic oscillation, and heating the resulting product to cause the sulfur generated by 
decomposition to in situ deposit to the pore path of the carbon material to obtain the sulfur / carbon composite material. According to the sulfur / carbon composite material, a sulfur particle and a 
carbon particle are tightly bound, the application of the sulfur / carbon composite material as the positive material of a 
lithium sulfur battery facilitates the reduction of solution loss of an active substance and the inhibition of shuttle effect, aluminum 
sulfide is generated from the 
ammonia gas and the 
hydrogen sulfide, which are generated by the 
decomposition of the aluminum 
polysulfide, through a condenser to be recycled, the technical process causes little 
pollution, the preparation method is simple in technology, low in cost and short in time, 
sulfur content is high, controllable, and strong in 
repeatability, and the sulfur / carbon composite material is easy for 
mass production.