The invention discloses a high-toughness and high heat conduction composite silicone gasket. The high-toughness and high heat conduction composite silicone gasket is prepared from the following components in parts by weight: 400 to 600 parts of alumina particles, 120 to 180 parts of dimethicone, 10 to 20 parts of polysiloxane, 1 to 8 parts of MQ silicon resin, 5 to 15 parts of methylvinyl siliconerubber, 3 to 8 parts of a silane coupling agent, 3 to 12 parts of a silica reinforcement agent, 1 to 3 parts of a catalyst and 0.3 to 0.8 part of an inhibitor. Compared with the prior art, the high-toughness and high heat conduction composite silicone gasket disclosed by the invention has the advantages that silicone components are reasonably proportioned, and the spherical alumina particles aresieved, so that the alumina particles are reasonably distributed in a silicone matrix and the heat conductivity coefficient of the alumina particles is improved; the silicone gasket disclosed by the invention has high insulating property; and in addition, the heat conductivity coefficient of the silicone gasket is improved to 6.0 W or above, which is out of reach by the prior art. Besides, the silicone gasket disclosed by the invention has superstrong toughness and can still keep higher toughness and strength in the preparation process of sheets.