The invention relates to the technical field of a grounding device, and specifically relates to an earth entry point anti-corrosion casing pipe for a grounding down conductor. The earth entry point anti-corrosion casing pipe for a grounding down conductor includes an outer pipe and an inner pipe which is provided with a cable hole for threading of a down conductor, wherein the inner pipe and the outer pipe are connected through reinforcing plates; the top and the bottom of the outer pipe are each provided with a protector, and the protector includes a first housing and a second housing matching the end portions of the outer pipe; a first fixing base is arranged on the inner surface of the first housing; a first gap matching the pipe wall of the outer pipe is arranged between the first fixing base and the first housing; a second fixing base is arranged on the inner surface of the second housing; connecting holes located at two sides of a first semi-circular hole are formed in the firstfixing base; and a connecting rod is arranged on the second fixing base. The earth entry point anti-corrosion casing pipe for a grounding down conductor is simple and convenient for installation, andcan achieve the enduring and effective anti-corrosion effect.