When traditional backfill materials are used for sheet pile wharfs，due to the self-weight of the backfill is heavy，it is easy to cause large vertical settlement of the wharf and large horizontal displacement of the front wall，which is not conducive to the overall stability of the wharf structure. In view of the above problems，a new material，foamed mixture lightweight soil is used as backfill material. The spatial three-dimensional model of sheet pile wharf structure and soil is constructed by PLAXIS 3D finite element software. The mechanical properties of the structure using the backfilling materials of foamed mixture lightweight soil and medium coarse sand on the upper part of the sheet pile wharf are calculated respectively. Through the comparative analysis of the results，it can be seen that when the upper part of the sheet pile wharf is backfilled with foamed mixture lightweight soil，there is a certain degree of reduction of the front wall bending moment，displacement and the pull rod tension，the overall stability and safety of the wharf is increased，which can provide a reference for similar engineering construction.