In order to explore the accuracy of the in-situ test results of the uplift piles under the foundation pit, the stress response and deformation law of the uplift piles under the excavation and unloading conditions were studied by changing the excavation range of the foundation pit by using the model test method, and then the bearing mechanism of the uplift piles was revealed. The results show that when the pile length is constant, increasing the depth of the foundation pit will greatly reduce the bearing capacity of the pile foundation and increase the slope of the load-displacement curve at the top of the pile. When the width of the foundation pit is greater than the critical value of "boundary effect", the increase of the width of the foundation pit has little effect on the bearing characteristics of the uprooted pile. Under the ultimate load, the normal stress of the pile is distributed in an approximately straight line along the length of the pile. When the depth of the foundation pit H value between 0.2 m to 0.6 m, the slope of the load-displacement curve is about 3.25 ~ 1.4 times of the unexcavated state.