Abstract: It is unaviodable to implement construction engineering along the planned urban rail transit, but It is necessary to consider in advance the impact of engineering project on the later rail transit construction, and vice versa to avoid the adverse effects on rail transit construction. In this paper, based on the reconstruction project of an office building in Nanchang County and the extension of Nanchang rail transit Line 3, a numerical analysis is carried out. The result shows that the displacement of stratum, tunnel internal force, foundation beam and pile foundation during subway construction could be reduced by increasing the pile length of buildings adjacent to subway tunnel. This research may provide a reference for similar projects.