This paper introduces the electric isolation protection technology of prestressed anchor cable and its testing method, further studies the main structural characteristics and technical performance of the double-layer electric isolation protection technology of anchor cable, and carries out the outdoor long-term electrical isolation protection performance monitoring and field testing in Taiwan. The results show that the OVM double-layer electric isolation protection cable, which adopts the combination of epoxy sprayed steel strand and cable bellows, can effectively implement electrical isolation protection under wet and other bad conditions, and the isolation resistance value of its permanent protection meets the requirements of European standards.