Abstract: In recent years, urban rail transit projects concerning abutment constructions that abuts existing underground structures have been springing out enormously. Under this circumstance, the safety assessment of both the impact on existing structures and the interactive influence between each other from construction within close range have become the key problem to be solved. Hefei rail transit line 3 was adopted as an example, where the main risks and influencing factors of building shield tunnel passing through the dangerous large arch bridge were analyzed and studied, and the corresponding countermeasures were put forward.