The composite system of cast-in-place pile wall and gravity structure is recommended for a wharf upgrading project in the Middle East. The system is able to make full use of the performances of the two structures and effectively solves the technical problems such as the forward movement of the berth line，deepening of berth water，significant increase in loading on the superstructure，strict requirements for horizontal displacement and rock foundation’s disturbance. The strength reduction method and the elastic-plastic analysis are used to carry out Plaxis finite element analysis of the main technical indicators of the composite structure，including the structural stability，the internal force of the pile wall and the horizontal displacement of the wharf. In addition，this paper compares the developing rules of structural stability，internal force and displacement under different horizontal stiffness of pile wall and tie-rod. The results show that the decreases in horizontal stiffness of pile wall and tie-rod can reduce the structural stability and pile wall’s internal force. The decrease in tie-rod’s horizontal stiffness causes the increase in the horizontal displacement，while the decrease in pile wall’s horizontal stiffness is beneficial to reduce the horizontal displacement to some extent.