In the process of urban construction, shield tunnel excavation will pose a great threat to the adjacent existing pile under high-speed railway. Driving isolation pile between the tunnel and high-speed railway foundation pile can effectively reduce the influence of the shield driving to adjacent pile foundation. In the field of pile-soil interaction, Winkler foundation model and Pasternak foundation model have been widely used. Based on these two foundation models, this paper uses the finite difference method by Maple mathematical software to analyse a practical engineering case. The calculated results are in accordance with existing engineering monitoring data. Then the influences of isolation pile of various parameters on the horizontal displacement of the pile under high-speed railway are further analyzed. The results show that Pasternak foundation model is more accurate than Winkler foundation model when the elastic modulus of isolation pile is smaller. With the increase of isolated pile diameter, the horizontal displacement of pile foundation will decrease significantly. The horizontal displacement of high-speed railway pile foundation can be reduced by reducing the horizontal distance between the isolated pile and the tunnel center line on the condition that the parameters of isolated pile remain unchanged.