The selection of square and rectangular steel tubes should be based on a comprehensive assessment of the project's purpose, load-bearing requirements, operating environment, and construction method. For load-bearing applications—such as factory building construction, steel structural frameworks, and equipment supports—specifications offering greater wall thickness and higher strength should be prioritized; conversely, for decorative projects, fencing, and lightweight structures, standard, cost-effective specifications are suitable. For outdoor applications, hot-dip galvanized tubes are recommended to enhance corrosion resistance and extend service life. Characterized by uniform cross-sections, ease of connection, and excellent workability, these tubes are widely used in steel-structure factories, curtain wall framing, warehouse racking, bridge engineering, machinery frameworks, and new energy projects. Selecting appropriate specifications not only ensures structural safety but also effectively minimizes material waste and reduces overall construction costs.