The invention relates to the field of thermal insulation materials and discloses a thermal insulation material. The thermal insulation material is prepared from raw materials, in parts by weight, including 70-100 parts of 1,6-diisocyanatohexane, 40-80 parts of polyether polyol I, 10-30 parts of polyether polyol II, 3-6 parts of expanded vermiculite, 5-8 parts of nano-silica, 10-20 parts of dichlorofluoroethane, 1-5 parts of a catalyst and 1-5 parts of a foam stabilizer by mixing and foaming, wherein polyether polyol I is lignin polyether polyol, and polyether polyol II is prepared from modified palm oil as an initiator and propylene oxide as a polymeric monomer through polymerization. The thermal insulation material has more excellent compressive strength, tensile strength and impact strength and avoids phenomena including deformation, bulging, corrugating and even cracking of a water tank.