The invention discloses a sulfur electrode material based on a solid-solid reaction mechanism and a lithium battery thereof, and a preparation method thereof. The sulfur electrode material based on the solid-solid reaction mechanism comprises polyacrylonitrile PAN, composite conductive carbon and elemental sulfur, the composite conductive carbon comprises pyrolytic carbon PANC prepared through high-temperature pyrolysis at a temperature of 300 degrees and 700 degrees and porous carbon BP2000, and the weight ratio of the PANC to the composite conductive carbon is 3.5-12.7%; and the weight ratioof the composite conductive carbon, the polyacrylonitrile PAN and the elemental sulfur is 1:10:50. The PAN pyrolytic carbon with a reversible lithium intercalation performance is synthesized, the PANpyrolytic carbon with the ratio of 3.5-12.7% coats the surface of the BP2000 with a high specific surface to prepare 6% of PANC@BP carbon of a lithium ion transmission conductor with high dispersity,the PANC@BP carbon is compounded with a PAN/S cathode material to construct a multiple composite sulfur electrode which generates solid-solid reaction on the sulfur-carbon interface; and moreover, the synthesized PANC@BP/PAN/S composite material has the good cycle performance and the higher reversible capacity.