Abstract: As cities develop, the development of urban underground space has expanded from the main roads to the smaller capillary-like areas. However, there is a lack of research on the soil response caused by small-diameter shield tunneling in soft soils. Using a 3.5 m small-diameter shield tunnel project in Tianjin Binhai soft soil, this study examines the impact of shield tunneling on the surrounding soil using on-site monitoring data and the Peck formula. The findings indicate that during shield tunneling, the horizontal displacement of the soil first increases and then decreases as it moves away from the tunnel side, while the lateral soil pressure first increases and then stabilizes before decreasing as it moves away from the tunnel side. The vertical displacement at the surface can be divided into four stages during shield tunneling. The surface settlement due to stratum loss is significantly greater than that caused by stratum consolidation, which in turn further increases the surface settlement. When the settlement stabilizes, the average width coefficient of the linear segment settlement trough is 0.37, and the average stratum loss rate is 0.73%. The parameters of the surface settlement trough caused by small-diameter shield tunneling are smaller for tunnels with diameters around 6 m, but similar to those for large-diameter (diameter > 10 m) tunnels.