The utility model relates to a sacrificial anode protective device for controlling external wall corrosion of a large-diameter pipeline, which is applied to a pipeline (1) for open-type excavating construction or pipe-jacking construction. The sacrificial anode protective device (3) is characterized by comprising the two following major parts specifically: a support connecting part (301) and a sacrificial anode part (302), wherein the sacrificial anode part (302) is directly or indirectly connected on the pipeline (1) fixedly by the support connecting part (301). The sacrificial anode protective device can guarantee the continuity of pipe-jacking construction of the pipeline, greatly save the installation work load and the installation cost, can achieve long-acting protection by primary construction, and meet the durability requirement of the large project construction; and the sacrificial anode protective device has foreseeable and enormous economic value and social value in project application.