Abstract: To explore the surface settlement law and the instability and failure mechanism of excavation face during shield tunneling in sandy cobble stratum, based on the shield project of Tsinghua Park tunnel, a shield tunneling model test was carried out in sandy cobble stratum by using the ϕ280 mm model shield test platform. The test results show that the transverse surface settlement trough is distributed asymmetrically towards the tunnel axis in sandy cobble strata, and the greater the stratum loss, the more significant the asymmetric distribution due to the rotation of the shield cutter head. On the other hand, the face active instability and failure develops from ground to surface with a lagging phenomenon. Meanwhile, the rotation direction of the cutter head has a direct effect on the location of the surface collapse pit. The center of the collapse pit is located on the side where the tangent of the cutter head rotates vertically upwards, which needs to be paid attention to in actual shield tunnel engineering.