In order to explore the variation of soil salinity and groundwater during crop growth period in semi closed irrigation area of Hetao irrigation district, the typical saline soil area in Wuyuan County, Bayannaoer, was selected as the study area. Based on fixed monitor of the regional soil-groundwater information, 149 sampling points and 30 groundwater observation wells were selected to collect data. Combined with classical statistics, spatial interpolation, and correlation regression analysis methods, the relationship between soil salinity and groundwater spatial dynamics, soil salinity, and groundwater depth was studied. The results showed that from April to October, the soil salt content of each soil layer decreased by 5.53% on average. The 1 m deep soil in the study area was desalinated, and the surface salt migrated to the deep soil. The main influencing factors of groundwater depth were irrigation water volume from the Yellow River, evaporation, and topography distribution in the study area. During the spring irrigation period (April to June), the average groundwater salinity decreased from 2.81 to 2.38 g/L, and the average groundwater salinity increased to 2.66 g/L from June to October. The groundwater mineralization was low during the spring irrigation period, increased after autumn harvest, and was high in the early spring irrigation from April to May. Due to the influence of irrigation and crop growth, the average soil salinity of 0—20 cm after autumn harvest decreased by 32.08%. During the growth period of crops, soil salinity migrated to deep soil (40—100 cm), and soil salinity was inversely proportional to depth, As the depth increases, the change in soil salt distribution gradually weakened. The area of 0—20 cm and 20—40 cm soil that had salinity greater than 4.0 g/kg in the same period was 85.63% and 9.71% in April, 42.37% and 15.86% in October. With the increase of soil depth from 40 cm to 100 cm, the decreasing trend of soil salinity tended to be gentle. With the increase of shallow groundwater depth, soil salinity gradually decreased, and effective measures should be taken to reduce the groundwater depth by 0.2 m, which is better to control within from 1.8 to 2.2 m.