The invention provides an aluminum-carbon composite material used for a tension-resisting joint fitting and a preparing method of the aluminum-carbon composite material. Aluminum powder and carbon powder dispersed in an organic solvent are evenly mixed, dried, subjected to ball grinding and pressed into an aluminum-carbon powder block; and the above aluminum-carbon powder block and an aluminum block are used as raw materials to be subjected to smelting, ingot casting, cogging and rolling, and a joint fitting material high in strength and resistant to loosening is obtained. The electric conductivity of the joint fitting prepared through the aluminum-carbon composite material is equivalent to that of pure aluminum. Due to the adding of carbon particles, the hardness, strength and high-temperature loosening resisting performance of the joint fitting are greatly improved. Due to the fact that carbon has very good stability in the atmosphere and does not form an alloy or a compound with aluminum, the corrosion resistance of aluminum is not obviously changed. Preparing steps are simple, operation is convenient, and practicability is high.