The invention discloses a high-flame-retardant and low-temperature-resistant cable protecting sheath. The cable protecting sheath is prepared from propylene homopolymer, silicone rubber, calcium hydroxide, a flame-retardant agent, plasticizer, stabilizer, and a crosslinking agent. The cable protecting sheath is excellent in flame retardance and low temperature resistance. Meanwhile, a method for preparing the cable protecting sheath is simple, and the raw materials are easy to obtain.