According to the vibration differential equation，the residual force vector expression was deduced in detail.As a structural damage index，the absolute value of the residual force vector was defined.By establishing high-piled wharf pile finite element model and using the residual force vector method，we carry out the numerical simulation for the pile of high-piled wharf damage diagnosis under a variety of conditions.The simulation results show that taking the residual force vector as diagnostic indicators are more sensitive to damage.The damage of structural can be identified quickly and accurately using low order modes parameters.