Considering the condition of Dazhongshan 1# shallow multi-arch tunnel unsymmetrical pressure in Shihong Expressway, and setting testing component in typical cross-sections, the tunnel's surrounding rock and supporting structure force are duly monitored. After the analysis of the monitoring date, according to site monitoring and information feedback, the surrounding rock deformation and supporting force were analyzed in-depth during the excavation of the tunnel and summarized the characteristics of force and deformation when the tunnel under unsymmetrical pressure. The results indicate that the tunnel has the inclination to the side of shallower depth of cover under the asymmetry, which makes an important role in guaranteeing the structure stability. Based on the engineering case, the article discussed the stability of tunnel during the excavation, which can provide reference for similar works.