The invention discloses a lightning arrestor used for the roof of a high-rise building. The lightning arrestor comprises a foundation pier and a casing pipe. A protrusion is arranged on the upper section of the inner wall of the casing pipe. An inner thread is arranged on the inner circumferential wall of the protrusion. The lower section of a connecting rod is matched with the protrusion through the thread. The upper section of the connecting rod is provided with a horizontally-arranged limiting pipe. A cylindrical direction-changing block is fixed to the middle portion of the limiting pipe. A straight hole is formed in the middle of the direction-changing block in the axis direction of the limiting pipe. Gaps are reserved between the two side walls of the direction-changing block and the inner wall of the limiting pipe. By adoption of the lightning arrestor, large-scale building roof lightning protection treatment can be fast achieved, the overall building attractiveness is not affected, and meanwhile, the difficulty and workload for laying a lightning strip are reduced; concrete is poured into a plastic pipe with a certain diameter, the casing pipe is pre-buried in the plastic pipe, the plastic pipe is directly removed after the concrete is solidified, and the foundation pier is formed; and the foundation pier is manufactured through drainage pipelines on a construction site and the building concrete, and the lightning strip laying cost is greatly lowered.