The excavation of the tunnel will inevitably cause the lateral movement of the surrounding soil, which will cause horizontal deformation and additional bending moments of adjacent pile foundations. At present, the modeling and calculation process of finite element numerical simulation is relatively tedious. In order to solve the problem of pile-soil interaction under tunnel excavation, based on Winkler foundation model, a two-stage analysis method was used to establish a passive pile stress analysis under tunnel excavation conditions. The governing equation of pile-soil interaction was derived and the approximate solution is given based on the finite difference idea. Finally, the results combined with the engineering example shows that the approximate solution is in good agreement with the field monitoring data and can effectively analyze the influence of tunnel excavation on adjacent pile foundations.