The invention discloses a high-temperature-resistant silicone rubber foam material and a preparation method thereof. The preparation method of the high-temperature-resistant silicone rubber foam material is characterized by comprising the following steps: mixing 100 parts of silicone rubber base stock, 20-35 parts of a reinforcing agent, 2-3 parts of a structure controlling agent, 0-0.2 part of colour master batch, 60-150 parts of a pore-forming agent and 4-5 parts of a radiation sensitizer, moulding, crosslinking through gamma ray radiation, forming pores through subsection dissolving-out, and drying, so that the silicone rubber foam material which is resistant to high temperature of 250 DEG C and still maintains excellent performance after equivalent time of 20000 hours can be obtained. The preparation method of the high-temperature-resistant silicone rubber foam material has the advantages that radiation crosslinking and dissolving-out pore forming are combined, so that crosslinking is uniform, control is easy, energy conservation and environmental protection are realized, a technology is concise, reproducibility is good, and production efficiency is high; the high-temperature-resistant silicone rubber foam material still maintains high tensile strength, high weight loss, low longitudinal deformation and low surface hardness after the equivalent time of 20000 hours at the temperature of 250 DEG C, permanent compressive deformation is slightly increased, the high-temperature-resistant silicone rubber foam material does not become brittle or hard, and the high-temperature-resistant silicone rubber foam material can serve as filling and positioning, sealing cushion, cable insulation as well as buffer and vibration-absorptive materials or parts which are used in high-temperature environment.