Abstract： The force of closely-spaced tunnel with super-large cross-section changes a lot because the flat rate becomes smaller. Aimed at the problem of displacement deformation characteristics and the pressure distribution of the surrounding rock in closely-spaced tunnel supporting design with super-large cross-section, and baseid on the two-hole eight-lane highway tunnel in Niu Zhai Hill, this paper established a three-dimensional finite element model considering the actual terrain and geology. It conducted a numerical simulation analysis of the  construction mechanical form of the tunnel under excavation, obtained the law of tunnel surrounding rock deformation during tunnel cons, and investigated the influencing law of proximity construction for closelyspaced large-section tunnel. The results show that the construction mechanical properties of closely-spaced large-section tunnel are complex. Due to the influence of bias pressure, the overall horizontal displacement of the surrounding rock is unsymmetrical distributed; the maximum horizontal displacement occurs in the spandrel of southline tunnel, the maximum subsidence of tunnel vault occurs in first hole, and the bulge at the tunnel invert is large. The stress concentrates in the invert and arch foot of the two holes. Based on these findings and considering the earthquake damage of tunnel entrance easily caused by bias pressure and ultrashallow cover, this paper performed dynamic finite element calculation after tunneling, analyzed the dynamic response under earthquake force of portal section, and evaluated its dynamic stability. The results provide basis for the optimal design, tunnel construction guidance and evaluation of tunnel stability and safety of supporting structure.