Abstract: In order to study the salt tolerance of Beta vulgar seedlings to NaCI salt at the third leaf stage, pot experiments were carried out with sugar beet variety H003 as the experimental material. The experiment consisted of 10 concentrations of NaCl, and the quality of NaCl in each treatment accounted for 0%, 0.1%, 0.2% ... 0.9% of the potted soil, respectively. Indicators were measured. The results showed that the fresh weight, dry weight and plant height of Beta vulgar reached the highest value at 0.2% salt treatment, and the fresh weight and dry weight at 0.5% stress treatment were significantly lower than the control, while the dry weight reached 0.7% stress treatment was significantly lower than the control. Chlorophyll and suporoxido dismutase（SOD）activity and quality indicators showed the same as the increase of NaCl concentration first increased and then decreased. Malondialdohydo （MDA） content and leaf plasma membrane permeability continued to increase with the increase of NaCl concentration. The growth of sugar beet was not inhibited under the soil NaCl stress of 0.4% or loss in the third leaf stage, and 0.1% - 0.2% NaCl soil environment promoted its growth.