Abstract: The material quality, processing technology and external force will cause the epoxy resin to form micro-cracks and reduce its insulation performance. To solve the problem of misrepair of one-component microcapsules, an epoxy resin composite medium based on two-component microcapsules was designed in this paper. The experimental results show that the healing rate of composite media increases with the increase of microcapsule content, and when the microcapsule mass fraction is 10%, the healing rate reaches about 85%. In addition, the curing temperature and working temperature will enhance the fluidity of the repair agent and accelerate the curing reaction rate, thus improving the repair speed. The insulation performance test shows that, with the increase of microcapsule content, the dielectric loss of the composite medium increases, the breakdown voltage decreases, but the flashover voltage increases first and then decreases. The main reason for the increase of dielectric loss is that the addition of microcapsules increases the interface polarization loss and orientation polarization loss. The main reasons for the decrease of breakdown voltage are the interface defects introduced by the addition of microcapsules and the high conductivity of microcapsules. When the microcapsule content is low, the trap defect density increases, thus the flashover voltage increasing first. When the microcapsule content is high, the liquid core material increases, the surface conductivity of the composite medium increases, and the flashover voltage decreases. After the scratch damage is repaired, the flashover voltage on the surface of the medium can be restored to about 105%-116% of that without repair.