The invention discloses a cable insulating material with good thermal stability and corrosion resistance. The cable insulating material is prepared from raw materials in parts by weight as follows: 15-35 parts of polyvinyl chloride thermoplastic elastomers, 15-25 parts of polypropylene, 10-20 parts of high density polyethylene, 5-10 parts of heavy calcium carbonate, 4-12 parts of glass fibers, 3-8 parts of barium sulfate, 2-8 parts of wollastonite, 1-6 parts of mica powder, 1-5 parts of modified lecithin, 0.5-1.5 parts of disproportionated rosin, 0.5-1.5 parts of chlorinated paraffin, 0.2-0.8 parts of liquid coumarone, 0.2-0.8 parts of pine tar, 0.2-0.8 parts of cresyl diphenyl phosphate, 1.2-1.8 parts of an antioxidant 1010, 1.2-1.8 parts of a stabilizer, 1-2 parts of an antistatic agent and 1-2 parts of a colorant. The cable insulating material has good thermal stability, high mechanical strength and excellent corrosion resistance.