The discontinuous stiffness of large-diameter steel tube and concrete combined pile leads to the complicated stress state at the joint part of the pile foundation and the base rock, the steel casing and the bedrock structure.So, it is needed to put forward a scientific basis to determine the pile foundation’s effective depth of embedment.Establishing the physical model and the numerical model of single pile with large-diameter steel tube and reinforced concrete combined force, we carry out numerical simulation and contrast test of a large number of variable parameters to probe into various factors affecting the lateral bearing capacity of the embedded piles and obtain the mechanical properties of the foundation under the action of the steel tube and the pile foundation.