β-Ga2O3 as a ultra-wide bandgap semiconductor material with a great development potential has a bandgap width of 4.8 eV, and a theoretical breakdown electric field of 8 MV/cm. Its Baliga advantage value of β-Ga2O3 is also several times greater than that of silicon carbide (SiC) or gallium nitride (GaN). However, the low thermal conductivity of β-Ga2O3 seriously affected the device's heat dissipation and the application in the high-power field. Wafer bonding is an indispensable key technology in semiconductor devices, which enables the formation of new structures, efficient fabrication, device integration, and cost reduction. The silicon substrate with the advantages of low cost and high thermal conductivity is an important substrate material for heterogeneous integrations. SiO2 layer is easily formed on the surface of silicon, and the surface structure of SiO2 consists of a Si–O–Si three-dimensional network structure together with an unsaturated Si–O structure, and the existence of this structure is conducive to reducing the probability of bubble generation, thus improving the quality of the bonding bonding interface, so it is easier to realize the bonding of silicon and β-Ga2O3 by using SiO2 as an intermediate layer. This paper was to analyze the effect of O2 plasma activation on the wafer surface, including changes in contact angle, roughness, and surface chemical composition. In addition, the effect of annealing temperature on the strength and thermal stability of the bond structure and the structure and composition of the β-Ga2O3/SiO2 bond interface was also discussed.