In order to study the stability characteristics of diaphragm wall trench wall in deep sand layer and its main influencing factors, the finite element model was established by numerical simulation method based on the construction of diaphragm wall trench in Liuzhoudonglu station of Nanjing Metro Line 11. The research results indicate that the development of surface settlement and horizontal displacement of the trench wall is mainly concentrated in the early stage of trench formation, while the changes in the later stage of trench formation are relatively small. At the end of the trench formation, the maximum surface settlement is 21.8 mm, occurring at a distance of approximately 3.6 m from the trench wall, and the impact range of the settlement is approximately 10 m from the trench wall. The maximum horizontal displacement of the groove wall occurs in the silty clay layer 4.4 m below the ground level. The reinforcement of the trench wall has a significant effect on controlling the instability of shallow soil during trench formation. The buried depth of the groundwater level has the greatest impact on surface settlement, followed by the depth of the slurry surface, the weight of the slurry, and the length of the trench section. The thickness of the soft soil layer has the smallest impact. The depth of the slurry surface has the greatest impact on the horizontal displacement of the trench wall, followed by the burial depth of the groundwater level, the length of the trench section, and the weight of the slurry, while the thickness of the soft soil layer has the smallest impact.