The response characteristics of forage rapeseed under Na₂CO₃ stress were studied. The variation characteristics of biomass, K⁺, Na⁺ transport, osmotic regulatory substances and protective enzyme activities of rapeseed under Na₂CO₃ stress were analyzed by setting the concentration gradients of 50, 80, 150 mmol/L of Na₂CO₃.The results showed that: With the increase of Na₂CO₃ concentration, the biomass of rapeseed decreased gradually. Na⁺ in roots and leaves increased gradually with the increase of Na₂CO₃ concentration, while K⁺ in stems decreased gradually with the increase of Na₂CO₃ concentration. Under the stress of Na₂CO₃, feeding rapeseed could balance the damage caused by malondialdehyde and proline to its membrane system by increasing the content of betaine, and meanwhile reduce the amount of reactive oxygen to maintain the stability of protective enzyme system.