The regularity of the deformation of the junction sections of tunnels in No. 14 bid section of BaojiLanzhou passenger dedicated line is studied on basis of the monitoring results, so as to improve the construction safety of critical positions of large crosssection loess tunnels. It is concluded that the intermediate bench excavation and the invert casting are critical points in terms of deformation development and deformation control. Furthermore, the maximum deformation of the junction section of No. 3 inclined shaft of Guchengling tunnel is predicted on basis of the study results, and the excavation method is optimized accordingly. In the end, the deformation of the mentioned junction section has been well controlled. 