Abstract:As a linear system identification method, the data-driven stochastic subspace method can effectively obtain modal parameters from the signal associated with structure under ambient excitation. Noise reduction ability of data-driven stochastic subspace identification method is related with its Hankel matrix dimension. We introduce theoretically the relation between noise and Hankel matrix of data-driven subspace identification method. And we also propose a verification procedure to justify the noise can be eliminated properly by data-driven subspace identification method with selected Hankel matrix, the procedure includes SVD, stability diagram and finite element result(FE). Finally based on data associated with numerical study and jacket platform vibration test separately, we demonstrate systematically that data-driven stochastic subspace identification method with non-square Hankel matrix has better capacity of denoising and estimating the modal with higher accuracy.