West Square of Hangzhou East Railway Station is a twostory largescale underground space developing project. With 10 m depth, the foundation pit is located above the running tunnel of Line 1 of Hangzhou Metro, with 673 m vertical clearance and 358 m influence length. In order to guarantee the safety of the operating Metro tunnel, layerbylayer and sectionbysection cutting of the foundation pit is simulated by FLAC 3D to evaluate the deformation and stress conditions of the Metro tunnel during foundation pit construction. It is concluded that layerbylayer and sectionbysection cutting of the foundation pit will not cause damage to the Metro tunnel. Furthermore, requirements for the monitoring of the Metro tunnel is proposed. The monitoring results show that layerbylayer and sectionbysection cutting of the foundation pit can guarantee the safe operation of the Metro tunnel. 