We propose a new method for threshold selection to improve the filtering effect. Based on theoretical analyze of spectral coefficients of phase fields, considering the scaling effect of fringe amplitude on spectral amplitude, we obtain fringe amplitude by using maximal spectral coefficients. Then, a new threshold about windowed Fourier transform filter method for speckle pattern interferometry is calculated. Through the verification of simulated speckle fringe pattern and real fringe pattern, the new threshold selection method can effectively filter out high-frequency noise, which performs better in filtering.