In order to accurately evaluate the control effect of groundwater compression mining on water salinization in Nantong City, the hydrogeological conceptual model of Nantong City is generalized according to the hydrogeological conditions of Nantong City, and a three-dimensional coupled numerical model for groundwater seepage and solute transport in Nantong City is developed to predict the variation trends of groundwater level and the mass concentration of Cl^- in groundwater from 2018 to 2034 under the present and compressed mining conditions, respectively. The results shows that by the end of 2034 the areas of the third confined aquifer with the mass concentration of Cl^- greater than 250 mg/L and 270 mg/L will reach 355. 17 km² and 30. 67 km², respectively, with the salinization rate of 9. 59 km²/a from 2030 to 2034 at current condition, while under the condition of compressed mining, the areas with the mass concentration of Cl^- greater than 250 mg/L and 270 mg/L reach 329. 21 km² and 1. 76 km², respectively, with the salinization rate of 7. 52 km²/a from 2030 to 2034, indicating that the compression mining scheme can effectively control the problem of water salinization in the third confined aquifer.