Dewatering is irreversibly damaging to railway foundation settlement. It is an important prerequisite to ensure the railway operation’s safety by proposing applicable foundation treatment structures and deformation prediction methods. Based on the actual investigation data of a railway in North China. A three-dimensional fluid-solid coupling model of railway foundation settlement induced by dewatering was established. The effects of the railway settlement are discussed under different dewater distances, flow rates, and depths. The applicability of pile network structures to improve foundation settlement was evaluated. Numerical and theoretical calculations show the occurrence of differential Settlement in the railway foundations under dewatering. This phenomenon was highlighted by the small pumping distances and the more depths and flows; The pile-net structure significantly reduces the deformation of the railway subgrade under different types of dewatering; Differential settlement results were shown in the theoretical prediction model. The problem of controlling the differential deformation in railway foundations needs to be limited by the fulfillment of conditions. This limitation may be erased with the establishment of the pile network structure.