<p>Soil salinity degrades fertile lands and jeopardizes agriculture. Common oats are resilient in harsh ecosystems. This study aimed to elucidate the salt tolerance physiological characteristics of oats and to identify key genes involved in salt tolerance. This study assessed the salt tolerance of oat resources via principal component analysis and membership function analysis, elucidated their tolerance mechanisms, and identified potential salt tolerance-related genes via physiology and transcriptome analyses. The salt tolerance of the four oat cultivars was highest in BY953, followed by Keyan1, BY896, and BY898. Under salt stress, BY953 maintained higher chlorophyll content, soluble sugar, protein levels, K⁺/Na⁺ ratio, and antioxidant enzyme activity compared to BY898, although BY898 showed a higher proline concentration. BY953 responded earlier to salt stress via three major pathways: proline metabolism, peroxisome, and ion transport. Weighted gene co-expression network analysis revealed three modules closely linked to salt stress in BY953, with the key genes <i>AsGF14B</i>, <i>AsPRMS</i>, and <i>AsUPL1</i> playing central roles. BY953 activates key genes involved in proline metabolism,&#xa0;peroxisome and ion transport during salt stress. This enables BY953 to maintain normal osmotic pressure, ensure the integrity of cell membranes, maintain a strong ability to scavenge ROS, and enhance the tolerance of root tissues and the ability of shoot tissues to excrete Na⁺ and retain K⁺ to tolerate salt stress. </p>