Abstract: ［Objective］ With the rapid development of urban rail transit in China, the excavation depth of station foundation pit diaphragm wall is increasing continuously, and the soil layers that are excavated through is becoming more complex. The direct object of diaphragm wall grab trenching is the soil, and the excavation resistance encountered by grab in different soil layers directly affects the construction costs and trenching quality/efficiency. However, there are few studies on the thrust resistance of diaphragm wall grab trenching, and most of them focus on engineering field such as river dredging, without comprehensively considering the impact of soil accumulation and slurry in grab on thrust resistance. Therefore, it is necessary to conduct targeted research on the thrust resistance calculation method in diaphragm wall grab trenching. ［Method］ Aiming at diaphragm wall hydraulic grab trenching construction, the failure, movement, and accumulation characteristics of soil in the excavation process are analyzed. Based on the existing model, the soil accumulation angle and slurry pressure in grab are introduced, and an improved calculation model of thrust resistance is constructed using plastic limit analysis method, and the corresponding calculation formula is derived. ［Result & Conclusion］ The error between the calculated results of thrust resistance during grab excavation by the constructed model and the experimental results is -0.55%. The availability of the derived model is verified, and the feasibility and correctness of considering the impact of soil accumulation and slurry pressure in grab when calculating grab thrust resistance are also proven, contributing practical application value.