Abstract：Research purposes： During the construction of the new bridge under the high-speed railway bridge, it is important not only to ensure the safety of the new project, but also to ensure the stability of the foundation of high-speed rail caused by pile construction and operation in a reasonable range. High speed railway track is characterized by high smoothness, and the limit of its foundation displacement is more stringent than the general bridge. Flac3D was used to analyze the foundation displacement of high-speed railway under the influence of new construction project during the construction of the New Interchange Ramp Bridge under the Harbin-Dalian Railway Passenger Dedicated Line. Based on the relevant standards, the impact of new construction on the high-speed rail foundation was evaluated. What＇s more, on the basis of the original scheme, the influence of the adjacent distance and the construction sequence on the results was analyzed.  Research conclusions：（1）The analysis results illustrated that in the cross region, pier No.439 was the most affected which is nearest from the new pile and the adjacent pier No.438 was affected by the second largest. The deformation of the two adjacent piers both conformed to the requirements of relevant codes.（2）Different proximity distance had great influence on foundation displacement of high-speed railway bridge. The smaller the distance was, the greater the foundation displacement was, and it was suggested that the minimum horizontal distance between the new pile foundation and the high speed iron base pile cap was not less than 3 times of the new pile diameter.（3）The influence of different construction sequence on the foundation deformation of high speed railway was relatively smaller. In order to reduce the influence of construction on the operation of high-speed railway, it was suggested to use the method of jump pile to pile foundation construction. （4）This research conclusion can provide reference for the construction of new bridge under high-speed railway in service. 