The invention discloses high insulation resistance refractory ceramic rubber for a heating cable and a preparing method thereof. The ceramic rubber is mainly prepared from, by weight, 40-45 parts of silicone rubber, 20-25 pars of ceramic powder, 15-20 parts of glass powder, 5-10 parts of quartz powder, 8-10 parts of mica powder, 5-10 parts of vapor phase method white carbon black, 0.5-1 part of coupling agent, 2-5 parts of softening agent and 0.8-1 part of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane. The preparing method comprises the steps of placing the raw materials in a rubber mixing mill for mixing, wherein mixing temperature is controlled to be 50-60 DEG C, and mixing time is 15-20 min; then conducting filtration with a rubber filter to obtain the required ceramic rubber, wherein the rubber filter is provided with three layers of filter nets, which are the 20-mesh filter net, the 40-mesh filter net and the 60-mesh filter net from inside to outside in sequence. The ceramic rubber has the advantages of being high in insulation resistance refractory property, good in dampproof insulation effect and long in service life. The operating temperature of the heating cable with the ceramic rubber as an insulating layer can reach 600 DEG C, dampproof insulation effect is good, safety performance is high, and breakdown of the cable can not be caused even if an outer sheath is abraded or soaked.