Salinity degrades the environment, reducing the productive capacity of affected land. This presents a significant challenge in agriculture; however, different crops are known to vary in their tolerance to salt stress. This study investigated the tolerance of two oat (Avena sativaL.) lines, Baiyan2 and Mengnongda1, to salinity stress. Oat lines were subjected to salt treatments (100 mM NaCl) for a two-week period and growth and physiological parameters of the two lines were compared. Salinity did not appear to affect the leaf and root dry weight of Baiyan2. In contrast, the leaf and root dry weight of Mengnongda1 showed a reduction of 42% and 35%, respectively. Additionally, leaf osmotic potential was higher in salt-treated Baiyan2 than in treated Mengnongda1 in all plant organs, suggesting that Baiyan2 is able to maintain better water status in saline conditions. Xylem proline concentration, sheath proline concentration, and proline contribution to sheath osmotic potential were also higher in salt-treated Baiyan2 than in treated Mengnongda1. Results also showed that salt-treated Baiyan2 retained similar levels of root potassium (K+) when compared to control plants, indicating that Baiyan2 has the capacity to maintain ionic homeostasis in root tissues in saline conditions. Contrastingly, salt-treated Mengnongdal seedlings showed a reduction of 34.3% in root K+. The sodium (Na+) and K(+)contributions to leaf osmotic potential were also higher in Baiyan2 than in Mengnongda1 under saline conditions, indicating that leaf Na(+)and K(+)may have a beneficial role in leaf growth of Baiyan2. Our findings suggest that Baiyan2 may have a physiological mechanism that confers a higher salinity tolerance. Accordingly, the Baiyan2 oat line may constitute an important source of germplasm for developing salinity tolerance in oats.