Brassinosteroids are a new group of steroid phytohormones that have high bioactivity and are widely spread in the plant kingdom. They are not only essential regulators of plant normal growth and development, but also can alleviate various abiotic stresses at very low concentration. This study evaluated effects of foliar spraying 24-epibrassinoide (24-EBL) on dry weight (DW), relative water content (RWC), osmotic adjustment ability (OAA), leaf gas exchange parameters, stomatal limitation values (Ls), the contents of Na⁺, K⁺, Cl^-, K⁺/Na⁺ ratio and S_K,Na in different organs of canola seedlings under 100 and 200 mmol/L NaCl. The results showed that: (1) DW of canola seedlings was decreased significantly under 100 and 200 mmol/L NaCl, however, 10^-12,10^-10, 10^-8, 10^-6 mol/L 24-EBL foliar spraying application all increased the DW of stressed plant. Also, 10^-10 mol/L 24-EBL (EBL2) treatments made the seedling DW peaked in both salt-stressed canola plants, and 29% and 20% higher than the values of only 100 or 200 mmol/L NaCl stress treatment, respectively. It was suggested that 10^-12, 10^-10, 10^-8, 10^-6 mol/L 24-EBL foliar spraying application alone made no significant difference to biomass accumulation of canola under non-salt treatment. (2) RWC of canola leaves was decreased under NaCl treatments, and EBL2 application promoted RWC and OAA of salt-stressed canola. (3) Under NaCl treatments, net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO₂ concentration (Ci) and transpiration rate (Tr) of canola leaves were declined at varying degree and limitation values (Ls) was increased markedly. However, EBL2 application partly reversed all the parameters at varying degree. (4) Compared with control, the contents of Na⁺ and Cl^- in leaves, petioles and roots of canola were increased significantly, while its K⁺ was decreased significantly. EBL2 application reduced the contents of Na⁺ and Cl^- in all canola organs, did not affected K⁺ content in the leaves significantly, and increased K⁺ content in petioles and roots. In general, the appropriate range concentration of foliar spraying 24-EBL obviously promoted salt resistance of canola seedlings. however, the optimal 24-EBL concentration of canola growth promotion was 10^-10 mol/L at each NaCl treatment level. The promotion of canola salt resistance was due to 24-EBL promoting the plant ion homeostasis and osmotic adjustment, then, improved plant water status and photosynthesis. Promotions of photosynthesis and water use efficiency in salt-stressed canola were owing to significant alleviation on stomatal limitation of stressed plant leaves caused by 24-EBL. The results also suggested that improvement of ion homeostasis in leaves caused by 24-EBL was as the result of exclusion of Na⁺ and Cl^-. However, not only exclusion of Na⁺ and Cl^-, but also K⁺ uptake increase was as the result of 24-EBL application contributing to ion homeostasis improvement in roots and stems.