The characteristics of four test methods, namely，high frequency force balance, forced vibration, aero-elastic model and rigidity model manometric test were compared firstly, then the differences between the results of rigid body base pivoted aero-elastic model (SDOF model for short) and multi-DOF aero-elastic model (MDOF model for short) tests were analyzed penetratingly. Wind tunnel tests reveal that the across-wind displacement of SDOF model is usually larger than that of MDOF model, especially when the wind speed is close to critical velocity of the crosswind resonance, and the reason for this phenomenon is the difference of vibration mode between two models, which could sensitively change the aero-elastic effects including aerodynamic damping,aerodynamic stiffness and wind pressure correlation. Finally, an improved design method of MDOF model, which was supported by one centered column and four ambient columns, was proposed base on above conclusions, which gives enough attention to the adjustability of high order frequency, torsion frequency and structure damping.