Abstract: Objective: When a new railway line constructed using shield tunnel underpassing existing tunnel in proximity, it can cause land subsidence, stratum deformation, uneven settlement, cracking, and even damage to the existing tunnels. Therefore, it is necessary to study settlement control measures for such projects to minimize construction risks and ensure the safe operation of existing tunnels. Method: Taking HangzhouHaining Intercity Railway underpassing Hangzhou Metro Line 1 as example, numerical simulation methods are used for analysis. The basic project overview and construction risk points are introduced. A computational model is established, the numerical simulation process is determined, and the calculated results of land subsidence under different construction working conditions are analyzed. Based on the parameters and implementation effects of the shield tunnel test section, the control parameters for the underpassing section are reasonably optimized, and the settlement control measures for shield tunnel underpassing existing metro tunnel are proposed. Result & Conclusion: (1) New railway line shield tunnel underpassing existing metro tunnel causes maximum settlement in the existing tunnels to be approximately 1.81 times the maximum land subsidence. (2) The periods of significant settlement during the above underpassing process are as follows: when the shield cutterhead of the new tunnel passes from below existing line left/right line tunnel middle part to below existing tunnel right line tunnel, and the new line shield cutterhead leaves the position 2d (d is the outer diameter of the new line shield tunnel) away from existing line right line tunnel until the end of construction. (3) During shield underpassing process, 5.7 m3/ring grouting volume, 0.30.4 MPa grouting pressure, 260270 kPa soil chamber pressure, 2.53 cm/min excavation speed, 5763 m3/ring dumping volume. Secondary grouting is implemented for excavation of every 2 rings and 0.30.5 m3/ring gram mud injection at each ring in areas with larger settlement. Fieldmonitored results show that existing line tunnel maximum settlement is about 1.73 times of land maximum subsidence, similar to the simulation calculation results.