Abstract: Based on Huangshandong Tunnel project, field data monitoring and numerical simulation by finite element analysis software of Midas GTS NX were used to analyze the laws of vault settlement, peripheral convergence and effective stress change of surrounding rock under different expansion widths. The length and ring distance of anchor bolts were changed to discuss the variation laws of effective surrounding rock stress, lining stress and bolt stress under different bolt lengths, and the optimal bolt length and bolt spacing under different expansion widths were determined. The results show that the decreasing sequence of effective surrounding rock stress is the compressive stress at the arch foot, the compressive stress at the arch waist, the compressive stress at the arch top and the tensile stress at the invert. With the increasing of excavation width, the compressive stress at the top of arch is decreased, while the compressive stress at the waist is increased with unconspicuous increasing trend. Under the influence of the single-side expansion mode, the stress of expansion side is greater than that of the non-expansion side. Due to the influence of stress concentration, the compressive stress at the arch foot is increased with the increasing of excavation width. For the expansion width of 1.5-2.5 m, the length and spacing of the anchor rod are respective 2.5 m and 1.7 m, and for the expansion width of 3.5-4.5 m, the length and spacing of the anchor rod are respective 3.0 m and 1.2 m.