In tunnel engineering, the disconnection of supporting and surrounding rocks is common. At present, most of the numerical studies of tunnels have assumed that supporting and surrounding rocks are closely con- nected without considering the influence of contact surfaces, which may lead to certain errors in the calculation results. In order to solve such problems, FLAC5.0 finite difference software was used to simulate and calculate the disconnection between supporting and surrounding rocks in shallow-buried tunnel in soft and hard stratum. The influencing factors of tunnel stability were analyzed. The calculation results show that the contact surface el- ement is more suitable for simulating the contact between supporting and surrounding rocks. When there is a gap between supporting and surrounding rocks, the displacement of surrounding rocks increases greatly while the in- ternal force of supporting has no remarkable differences, which can provide better guidance for design and con- struction.