Abstract: Described here in the article are the general situation and main technical requirements of the Yangtze River Shield Crossing Project, focusing on the performance characteristics of the API Spec 5L X80 Φ1 422 mm×32.1 mm UOE 18 m elongated SAWL steel pipe as developed by Baosteel for said the project with the integrated manufacturing technology. It is revealed via the analysis that the X80 steel pipe has ultra-low C content, high Mn and Nb content, fine microstructure, high strength and toughness, and good weldability, which meets the requirements by the project. The successful development and application of the above mentioned elongated steel pipe have filled the gap of the extra heavy and extra long X80 large-sized UOE SAWL steel pipe for river-crossing tunnel projects both at home and abroad.