Square tubes are classified by production process: hot-rolled seamless square tubes, cold drawn seamless square tubes, and extruded seamless square tubes. Initially, our company mainly produced square tubes using a stockpiling method. Through technical accumulation, our hot-rolled seamless square tubes have now completely replaced the extruded tubes. Producing square tubes via the hot-rolling method presents significant research challenges. Not only do they require high toughness and ductility to pass fatigue performance evaluations, but also high dimensional accuracy is needed, as well as careful selection of steel grades and tooling requirements. To ensure a smooth experimental evaluation, the technical department and production division persisted in overcoming difficulties, and the square tubes produced not only possess excellent strength and ductility matching but also excellent low-temperature toughness and good dimensional accuracy.