Abstract: In some mountainous areas, the geological condition is that the upper part is soil while the lower part is rock. In order to solve the difficulty of manual excavation in pile foundation, in this paper we analyzed the pile-rock anchor composite foundation, and put forward the key technical points of its design. Compared with traditional foundation, the results show that:under the premise of bearing capacity, the pile-rock anchor composite foundation is superior to the traditional foundation in the amount of reinforcement, the amount of concrete and the construction speed. Pile-rock bolt composite foundation has good technical and economical effect in high voltage overhead transmission line, so it has good promotion effect in engineering application.