Inspired by unparalleled adhesion of mussels, bio-inspired poly(dopamine) (PDA) has been used to functionalize the surface of aluminium oxide (Al2O3) nano-particles aiming at improving thermal conductivity of silicone rubber (SR). The successful and effective preparation of PDA modified Al2O3 nano-particles (Al2O3-PDA) was confirmed by XPS, HR-TEM, and XRD. The PDA coating on the Al2O3 nano-particles improved its interfacial interaction between polymeric matrix and facilitated the uniform-dispersion of filler, leading to the 30 vol% Al2O3-PDA/SR composite exhibited a high thermal conductivity (0.585 W/(mK)), which was almost 400% of pure silicone rubber (0.147 W/(mK)). In addition, the 30 vol% Al2O3-PDA/SR composite displayed a relatively low dielectric constant (4.06 at 1 kHz), which was a bit higher than that of pure SR (2.59 at 1 kHz), a big advantage for the electronic or electrical engineering application. With advantages of efficient, easy handling, controllable, and eco-friendly, this modification method provides a new universal route to improve the thermal conductivity of composites.