Based on a cross-tunnel bridge construction project,the effects of two factors -the distance between tunnel and pile (S) and the length of the pile (L) on the tunnel deformation are analyzed in the FLAC3D model. The results showthat the vertical displacement of the tunnel and S are approximately piecewise linear. In order to ensure the stability of the tunnel structure during the construction of the pile foundation,S should not be less than 6m;Relative position between pile and the tunnel is determined by the length of pile,the bottom of the pile should be avoided at the arch of the tunnel.