Abstract: 【Objective】 This study aims to investigate the influence and threshold of different types of saline-alkali stress on the germination of cotton seeds. 【Methods】 Four types of saline-alkali stress and seven concentration levels were simulated by Petri dish method. Cotton seeds of Xinluzhong 84, Tahe 2, Xinluzhong 40 and Jiumian 18 were used as research objects. The germination potential, germination rate, germination index, seed vigor index, fresh weight and dry weight of seedlings after germination were analyzed, salt tolerance threshold and membership function values were calculated, and comprehensive evaluation was carried out. 【Results】 (1) The germination potential, germination rate, germination index, vitality index, fresh weight and dry weight of cotton seed after germination showed a significant downward trend under the four types of saline-alkali stress. There was a significant negative correlation between saline-alkali concentration and all indexes, and the correlation between saline-alkali concentration and germination rate was more than -0.90. (2) The salt tolerance thresholds of cotton at germination stage were different under the four types of saline-alkali stress conditions. The salt tolerance thresholds under S₁ stress ranged from 90.70 to 121.73 mmol/L. The salt tolerance threshold under S₂ stress ranged from 82.68 to 128.30 mmol/L. The salt tolerance threshold under S₃ stress ranged from 51.97 to 84.62 mmol/L. The salt tolerance threshold under S₄ stress ranged from 73.49 to 98.21 mmol/L. (3) The salt tolerance of cotton seeds under four kinds of saline-alkali stress was analyzed by membership function and its order was Xinluzhong 84 > Xinluzhong 40 > Tahe 2 > Jiumian 18 under S₁ stress, Xinluzhong 84 > Tahe 2 > Xinluzhong 40 > Jiumian 18 under S₂ stress, and Tahe 2 > Xinluzhong 40 > Xinluzhong 84 > Jiumian 18 under S₃ stress. It was found that the order of salt tolerance of cotton seeds under S₄ stress was consistent with that under S₂ stress. 【Conclusion】 The germination potential, germination rate, germination index and vigor index of cotton seeds are decreased under the four types of saline-alkali stress, and the fresh and dry weight of seedlings shows a downward trend with the increase of the concentration. The effect of alkaline salt on the germination of cotton seed is obviously greater than that of neutral salt.