Due to ignoring the influence of foundation pit unloading effect on the bearing properties of uprooted piles, the accuracy of in-situ test results needs to be studied when the excavation unloading area is large, and the current research on uplift piles mostly reflects the bearing properties of piles based on pile side friction resistance, and there are few studies on the normal pressure of pile-soil interface on pile sides. Compared with the frictional resistance of the pile side, the normal pressure of the pile-soil interface on the pile side can intuitively reflect the influence of foundation pit excavation and unloading on the bearing properties of the uprooted pile. In view of this, the combination of model test and numerical simulation was used to explore the stress response and deformation law of uplift piles under excavation and unloading conditions by changing the variables such as foundation pit excavation range and pile roughness, and then the bearing mechanism of uplift piles was revealed. The results show that the unloading effect of foundation pit excavation is related to the depth and width of the foundation pit, the effective pile length and the pile side roughness, according to the degree of influence: the effective pile length > the depth of the foundation pit > the roughness of the pile side > the width of the foundation pit. When the width of the foundation pit is greater than the critical value, the increase of the width of the foundation pit has little effect on the bearing characteristics of the uplift pile. Under the condition of the same effective pile length, the normal stress of the excavated pile side is proportional to the depth of the foundation pit and inversely proportional to the width of the foundation pit, and the relationship with the pile roughness is small. Under the condition of the same effective pile length, the frictional resistance of the pile after excavation is directly proportional to the depth of the foundation pit and the roughness of the pile, and inversely proportional to the width of the foundation pit.