The achieving of high-level mechanical reinforcement and efficient healing in intrinsic self-healing composite is challenging because the contradictory in chain mobility associated mechanism. Here we show that the covalent incorporation of molecular-scale polyhedral oligomeric silsesquioxane (POSS) by dynamic bonding into self-healing polymer can simultaneously realize these two requirements. The exemplified disulfide-based organic/inorganic hybrid dynamic network is directly constructed by a bottom-up strategy from pentaerythritol tetrakis (3-mercaptopropionate), glycol dimercaptoacetate and octathiol-POSS via oxidative coupling among thiol groups. It is showed that a 7 times improvement in modulus, 3 times increase in tensile strength, and 4.9 times increase in toughness can be simultaneously achieved by incorporation of 10 wt% POSS into the optimized disulfide-based matrix. As a result of the ultrasmall size of POSS and the dynamic interphase among POSS and matrix, the hybrid network exhibits comparable relaxation behavior with that of matrix and can be completely healed at moderate temperature.