Abstract: The effects of different concentrations of NaCl (0, 0.1%, 0.3%, 0.5%, 0.7%, 0.9%) on growth of alfalfa (Medicago sativa) (survival rate, root length, stem length, leaf number) and the contents of Na⁺, K⁺, Ca²⁺, Mg²⁺ in the different organs were assessed and the ratio of K/Na, Ca/Na, and Mg/Na were analysed. The survival rate, root length, and stem length were all negatively correlated with salt concentration, except when the NaCl concentration was ≤0.1%. The content of Na⁺ in root, stem and leaves and the content of Ca²⁺ in roots were all positively correlated with salt concentration. However, the contents of K⁺ and Mg²⁺, and the ratios of K/Na, Ca/Na, Mg/Na in roots, stems and leaves significantly decreased with an increase of salt concentration. Salt stress on alfalfa caused significant differences in the comparisons. The reason for salt injury and salt-tolerance in alfalfa are discussed in relation to ion toxicities.