Based on the actual project of a multi arch tunnel in Northern Shaanxi, to study the deformation characteristics of surrounding rock during the construction of shallow buried multi arch tunnel with weak and broken surrounding rock, the long-term tests of vault settlement and surrounding rock deformation were carried out by laying certain monitoring instrument on site, while the laws of vault settlement and surrounding rock radial deformation during the construction process were obtained. The results show that: the surface settlement is similar to peck settlement curve. The closer to the center of the tunnel, the greater the surface settlement is. The maximum settlement value is about 12.1 mm after the excavation of the left tunnel, and the variation of vault settlement along the longitudinal direction of tunnel is as follows: middle pilot tunnel > main tunnel > left and right pilot tunnel. The middle pilot tunnel shows a vault settlement, while the side pilot tunnel shows a horizontal convergence. The convergence deformation of the upper step construction is significantly greater than that of the lower step construction because of no temporary invert bottom sealing. With the increase of the distance from the tunnel wall, the cumulative deformation of the measuring point decreases gradually. The surrounding rock loose area of K21+970 test section is about 2 m, and the loose area of K21+970 test section is more than 4 m due to the limitation of the layout of the measuring line.