Abstract: 【Objective】 To explore the effect of winter irrigation on water and salt regulation of saline-alkali soil under irrigation and drainage coordination. 【Methods】 Based on field soil box test, two kinds of groundwater depths (G₁ (2 m) and G₂ (3 m)) and two irrigation methods: (W₁ (winter irrigation) and W₂ (non-winter irrigation)) were set, and the freeze-thaw characteristics of soil under different irrigation methods, the characteristics of soil salt return during non-growth period, the efficiency of salt leaching and drainage under winter irrigation combined with irrigation and drainage, and the emergence and seedling growth of cotton were studied. 【Results】 Winter irrigation delayed the daily freeze-thaw cycle and daily ablation cycle of soil, and the duration of freeze-thaw and ablation after winter irrigation was shorter than that of non-winter irrigation.With the increase of soil depth, the freezing time lagged behind and the freezing duration became shorter.Winter irrigation could effectively wash the salt of 0-60 cm soil layer, and the salt drainage of 2 m groundwater depth was greater than 3 m.Before sowing in the next year, there was a significant difference in soil salt accumulation between winter irrigation and non-winter irrigation in 0-20 cm soil layer, and the salt of non-winter irrigation was higher than that of winter irrigation.Under the same irrigation method, the surface salt return amount of 2 m groundwater depth was greater than 3 m; at the same underground water depth, the salinity return degree of winter irrigation waS lower than that of non-winter irrigation.There were significant differences in cotton emergence and seedling growth after drip irrigation in the next year, and the emergence rate and seedling growth in the next year after drip irrigation were better than those after drip irrigation. 【Conclusion】 Winter irrigation can reduce the soil temperature potential difference at the air-soil interface, reduce the duration of freeze-thaw alternations of 0-20 cm soil, inhibit soil salt return, and promote the growth and survival of cotton seedlings in the next year.Under the coordination of irrigation and drainage, the higher the groundwater depth of underground drainage, the lower the salt carrying efficiency.In the irrigation area, the salinity can be washed into the rising groundwater by winter irrigation, which is characterized by weak diving evaporation and weak salt return.In the spring warming period, groundwater is extracted timely, and the rapid salt return of soil surface is suppressed by reducing the groundwater level, so as to achieve the dual function of inhibiting salt return by drainage irrigation.