Abstract: To investigate the stability and stress-deformation characteristics of surrounding rock during the excavation of large-section tunnels via the double-side drift method under complex geological conditions, this study takes the Xingyuan No.1 Tunnel Project as the case study. It examines the excavation process of large-section tunnels by integrating finite element difference calculations with on-site construction monitoring. Based on the measured data from the tunnel construction site, a comparative analysis reveals that the finite element simulation results of double-side drift method excavation are highly consistent with the actual monitoring outcomes, thus validating the accuracy of the finite element simulation model for large-section tunnel excavation. Meanwhile, the established finite element model is further utilized to analyze the stress-deformation characteristics of surrounding rock during the excavation of large-section tunnels using the double-side drift method. The calculation results demonstrate that during tunnel excavation with this method, the tunnel vault reaches the maximum vertical displacement, while the tunnel haunch exhibits the maximum horizontal displacement; accordingly, reinforcement of the tunnel vault support is essential during construction. The findings of this study can provide guidance for the on-site construction of the Xingyuan No.1 Tunnel Project and offer a quantitative basis for the support design of large-section tunnels.