Structural signal is taken self-adaptive decomposition by Hilbert-Huang Transform mainly composed of the EMD(empirical mode decomposition) and HT(Hilbert Transform), which is especially suitable for structural projects in the non-linear, non-stationary signal analysis through local characteristic. However, some weak signal may be ignored by EMD resulting in modal missing. Butterworth filter is an electronic filter designed to have flat frequency response. Considering the influence of noise , Hilbert-Huang Transform and Butterworth band pass filter are applied together to process the structural signal in order to obtain the frequency, damping ratio and mode shapes of the structure more precisely in this paper. Numerical Simulation results show that the proposed method in this paper could identify the modal parameters effectively and accurately.