GMS model is a widely-used system in groundwater simulation. This paper took a town in Kunshan as a study area tosimulate the hydrological conditions and water quality of the groundwater using the GMS model. The conceptual and mathematicalmodel was established with generalized method, and the main parameters of the model was calibrated with iterative method, andthen MODFLOW and MT3DMS were used to simulate and forecast the hydrological condition and water quality and migrationtrends of pollutants in the study area. The results show that the simulated values are consistent with measured values, which meansthat the calibrated GMS model can better reproduce the characteristics of the underground water with strong reliability, and can beapplied to simulate and forecast migration trends of pollutants in watersheds.