The extraction of groundwater will lead to a drop in water level, causing a change in the distribution of additional stress in the strata. This phenomenon leads to uneven settlement of the railway subgrade. In severe cases, this could pose a threat to the safe operation of trains. Therefore, it is necessary to first identify the primary subsidence areas of the railway and investigate the impact of various parameters on them. Taking the deformation of railway subgrade as the research object, this study utilizes InSAR technology to investigate the regional subsidence trends and determine the significant locations of railway subsidence. Subsequently, based on the Biot consolidation theory of the soil, a numerical simulation model was established to study the impact of different parameters of the groundwater extraction on site. Finally, corresponding treatment measures are formulated. The results shows: (1) The extraction of underground brine has caused a maximum subsidence rate of 189 mm/y in the study area, and the subsidence rate on the railway reached 14.5 mm/y; (2) The distance between the well and subgrade, the amount of water pumped, and the number of water wells all have a significant impact on subsidence and should be focused on; (3) Adjusting fasteners and using the horizontal jet grouting pile reinforcement technique can improve the ability of the road and structure to resist deformation.