As a new type of sheet pile structure，steel pipe pile/AZ steel sheet pile composite wall has the advantages of simple structure，large bending stiffness，small deformation,economy and broad application prospect. It has never been applied in large-scale deep water docks in domestic engineering instance，therefore the characteristics of the structure remain to be further investigated.According to a wharf project，we explore the mechanical properties of this type of composite wall by using the vertical elastic foundation beam theory，also the influence of pile-soil interaction is considered.The result shows that pipe/AZ combined steel sheet pile has greater bending stiffness than the traditional structure，and it has good economy due to the reasonable stress distribution of horizontal soil arch structure.Combined wall displacement deformation is small，then horizontal displacement meets the use requirements.