Abstract: Short carbon fiber reinforced TDE-85 epoxy resin composite material was prepared, the effects of carbon fiber content on the mechanic properties and heat resistance of composite material were studied. The results show that the mechanical properties and thermal stability of composites could be improved obviously by adding carbon fiber, as the content of carbon fiber was 0.25%, the tensile strength, impact toughness, flexural strength and flexural modulus were maximum, increased by 29.33%, 25.31%, 30.28% and 68.93%. In addition, the morphology of the bending fracture surface of the composites were analyzed, the results show that a certain amount of carbon fiber can be well dispersed in the resin matrix, besides, the precursor of carbon fiber and resin matrix interfacial bonding was relatively weak, as mainly depends on the physical fitted between the carbon fiber and resin matrix.