In order to solve the problems of complex precursor preparation and cumbersome process in the synthesis of functionalized MQ silicone resins, an efficient one-step synthesis strategy based on benzocyclobutene (BCB ) modification was developed in this study. Thermally crosslinkable BCB-MQ silicone resin was successfully prepared by introducing BCB functional groups with low dielectric constant and high thermal stability directly onto the silicon-silicon backbone through acid-catalyzed hydrolysis condensation reaction. The effect of the mole ratio of DVS-BCB to ethyl orthosilicate (TEOS) on the properties of the cured resin was systematically studied. The results show that when n( DVS-BCB) ∶ n(TEOS) = 0.8, the cured resin exhibits the best overall properties, a dielectric constant (D_k, 10 MHz) as low as 2.70, a 5% thermogravimetric temperature (T_5%) up to 462.3 ℃, and an elastic modulus of 3.9 GPa. The short glass fiber-reinforced composite prepared by hot pressing further exhibits excellent mechanical and dielectric properties, with tensile strength and flexural strength reaching 52.7 MPa and 122.3 MPa respectively, and a dielectric constant of 3.77. The BCB-MQ silicone resin has good compatibility with silicone rubber/ silicone resin and thermal cross-linking characteristics, and its performance is better than that of the traditional silica filling system, and has broad application prospects in the field of high-end electrical insulation materials and nuclear power equipment fields.