In this investigation, 3-glycidoxypropyltrimethoxysilane and boric acid with the molar ratio of 1, 2, and 3 were used to synthesize different structures borosiloxane oligomers (BSiO-1, BSiO-2, and BSiO-3). The structures of these borosiloxane oligomers were evaluated by the gel permeation chromatography, the Fourier transform infrared spectroscopy, the nuclear magnetic resonance spectroscopy, and the thermogravimetric analysis. The influence of borosiloxane oligomers structures on adhesion between addition-curable liquid silicone rubber and epoxy networks was investigated by pull-out test. Results showed that BSiO-1 and BSiO-2 exhibited excellent adhesive property with the adhesion strength being increased from 0.02 to 0.18 MPa, whereas BSiO-3, with an adhesion strength value of 0.1 MPa, displayed a slightly inferior adhesive characteristic. Field emission scanning electronic microscopy revealed the attenuation of adhesive characteristic of BSiO-1, BSiO-2, and BSiO-3 in turn, and an adhesive attenuation mechanism was proposed.