Abstract: The two main functions of cement mixing piles are retaining and sealing in protecting foundation excavations. The current methods believe that the retaining structures bear the pressure of soil and water and the sealing curtain prevents groundwater from infiltrating pit. Generally they do not consider the effect of curtain on the decreasing deformation. First, soil and water pressure deliver to the curtain, and then pass to the bored pile indirectly. If the two parties are regarded as a whole envelope, the curtain will increase the overall stiffness and weight, thereby increase the overall stability. The effects of various water-resisting curtain depths, water-resisting curtain rows, distances from water-resisting curtain to bored pile and physico-mechanical parameters of water-resisting curtain on normalized wall deflections are studied. When the curtain depth increases from the excavation depth to bored pile length, the lateral displacement of foundation pit decreases significantly. As the curtain depth continues to increase, the lateral displacement of foundation pit will continue to decrease, but the reduction is not obvious. When the rows of curtain increase, the lateral displacement of foundation pit decreases significantly. Especially from two rows to three rows, there is a large percent of decrease.