The invention relates to a rock anchor foundation structure applicable to a mountain photovoltaic assembly and a construction method thereof to solve the problems that existing mountain photovoltaic power station foundation construction is low in efficiency and high in cost and to improve the load-bearing capacity of a foundation. According to the technical scheme, the rock anchor foundation structure comprises a drill hole drilled in a rock slope, an anchor rod assembly arranged in the drill hole, and a photovoltaic power station assembly; the photovoltaic power station assembly is connected with the anchor rod assembly through hollow connecting steel tubes; the anchor rod assembly comprises a hollow anchor rod, and a plastic anchor head assembly, a slurry stop plug, a steel base plate and a fastening nut which are used in cooperation with the hollow anchor rod, wherein the hollow anchor rod is inserted into the drill hole, and the surface of the hollow anchor rod is provided with a continuous waveform thread; the space between the hollow anchor rod and the drill hole is filled with mortar anchoring bodies for fixing; and the photovoltaic power station assembly comprises supports welded to the tops of the hollow connecting steel tubes, a cross beam hinged to the tops of the supports, and a photovoltaic cell panel arranged on the upper portion of the cross beam. The rock anchor foundation structure applicable to the mountain photovoltaic assembly and the construction method thereof are suitable for the technical field of ground foundation treatment and foundation engineering design.