The invention relates to the technical field of power transmission line iron towers, and provides a power transmission line iron tower. The aim is to solve the problem that an existing iron tower bodyis not sufficient in stability, and the power transmission line iron tower comprises a base, an iron tower body structure and a middle supporting structure; the iron tower body structure and the middle supporting structure are vertically arranged on the base, and the middle supporting structure is located in the middle of the iron tower body structure; an installing groove is formed in the top ofthe base, a footing is arranged inside the installing groove and provided with an internal thread, an external thread is arranged at the bottom end of the middle supporting structure, and the middlesupporting structure is connected with the footing through the threads; the middle supporting structure comprises multiple inner connecting tubes and multiple outer connecting tubes, the inner connecting tubes are provided with external threads, internal threads are arranged on the outer connecting tubes, every two adjacent inner connecting tubes are connected through the corresponding outer connecting tube, and the two ends of the outer connecting tubes are in threaded connection with the inner connecting tubes respectively. The power transmission line iron tower has the advantages that the stability of an iron tower main tube can be improved, meanwhile, the structure is simple, construction is convenient, and manufacturing costs are low.