The invention discloses an SEBS thermoplastic elastomer cable insulation material which comprises the following components in parts by weight: 100 parts of SEBS resin, 50 to 150 parts of rubber filling oil, 10 to 50 parts of grafting modified SEBS, 50 to 80 parts of polypropylene, 15 to 30 parts of polyolefin elastomer, 100 to 200 parts of mineral filler, 2 to 5 parts of lubricant, 2 to 4 parts of anti-aging agent and 1.8 to 3 parts of copper ion inhibitor. The invention also provides a preparation method of the SEBS thermoplastic elastomer cable insulation material, which comprises the following steps: raw material weighing, mixing and granulation. The SEBS thermoplastic elastomer cable insulation material has excellent electrical insulation performance as well as good mechanical performance and aging resistant performance, is a novel material capable of substituting soft vulcanized rubber, is used for soft cable insulation layer production, realizes the full 'vulcanization-free' of soft cable production, and is characterized by 'safety, environment protection, energy saving' and the like.