The invention relates to high-temperature resisting bonding sealed silicone resin and a preparation method thereof. The high-temperature resisting bonding sealed silicone resin is prepared from the following raw materials: methyl phenyl polysiloxane-b-polyphenylsilsesquioxane block copolymer resin, methyl phenyl hydroxy silicone oil, functional POSS (Polyhedral Oligomeric Silsesquioxane), heat-resisting filler, an adhesive, a cross-linking agent and a catalyst. The preparation method comprises the following steps: firstly, mixing the methyl phenyl polysiloxane-b-polyphenylsilsesquioxane block copolymer resin, the methyl phenyl hydroxy silicone oil and the functional POSS, and then carrying out vacuum stirring and dehydrating at the temperature of 100 to 120 DEG C for 1 to 2 hours; secondly, adding the heat-resisting filler and the cross-linking agent for carrying out vacuum stirring for 30 to 60 minutes, then adding the adhesive and the catalyst for carrying out vacuum stirring for 30 to 60 minutes, discharging and sealing to obtain the high-temperature resisting bonding sealed silicone resin. The resin has the advantages of better heat-resisting property and mechanical property, and no need of white carbon black for reinforcing and priming; in addition, the retention rate of shear strength is more than 90 percent after the resin is subjected to 400 DEG C*1 hour high-temperature treatment, and tensile strength, shear strength and peel strength are still more than 80 percent after the resin is subjected to 330 DEG C*24 hour treatment.