The substitute structure method is one of the main methods for the determination of seismic displacement demand in displacement-based seismic design method of pile-supported wharf，and equivalent damping ratio is the key parameter of that method. However，there are great differences in the calculation models used in different wharf seismic design codes，and some other models are specially proposed for wharf in literature. To analyze the influence of damping models on the seismic displacement demand，we utilize the substitute structure method and nonlinear time-history analysis method to conduct demand analysis for three wharves respectively. During the analysis for substitute structure method，we adopt four damping models from codes and literature，determine the ratio of displacements from the two methods，and perform the statistical analysis for displacement ratios. The results show that the average ratios of the displacement obtained from the nonlinear static analysis to the displacement obtained by the nonlinear dynamic time history method of the four damping ratio models are between 0.8 and 1.2，and the displacement ratios conform logarithmic normal distribution. The accuracy of damping equations for codes is generally lower than that of equations from literature. For cast-in-situ concrete and steel piled wharves，the equation from design criteria for Port of Long Beach shall be adopted for analysis. The equation from ASCE/COPRI 61-14 shall be utilized for pre-stressed concrete pile wharf with magnification factors of 1.10，1.25 and 1.65 for ensurance probabilities of around 50%，75% and 95% respectively to improve the reliability of results.